Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Â*Â* When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
.. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !


It´s classic for sure. The power wire is bouncing around as you drive, and
over time the wire insulation was worn through, allowing contact between
copper wire and some part of the steel body.When you find the spot, it will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically prevent
further contact.

Joe Gwinn

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"Terry Coombs" wrote in message
...
When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply .
He did tell me that the radio had "died" , turns out the fuse (in
the fuse block) keeps blowing . I've got the dashboard apart enough
to check the wiring harness and supply wires , can't find any cuts
or anything that looks like damaged insulation ... it works just
fine sittin' in the driveway , but within a few miles driving it
blows the fuse . I figured it was the radio/CD player unit so I got
a new one , does the same thing . I'm really puzzled by this , from
the way the fuse was spattered it's got to be a dead short to ground
. I think it very unlikely that the new radio/CD unit is bad - the
old one did work when I replaced the fuse , for a few miles same as
the new unit . This is an '86 GMC pickup , I'm hoping someone here
might be aware of a known problem area that I might check ... I
gotta have tunes !

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !


Check/clean the battery connections.

If connector vibration momentarily disconnects the battery from the
charging circuit, the alternator output voltage will rise until a
protective clamping device somewhere, like in the radio, conducts
enough current to limit it. The voltage regulator tries to cut off the
alternator field current but can't remove the current already flowing
in the field winding.

https://en.wikipedia.org/wiki/Load_dump



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On Tue, 24 Sep 2019 07:58:47 -0500
Terry Coombs wrote:

Â*Â* When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !


Just some random ideas... Does it have a power antenna? (doubtful)

Check the fuse schematic and see if anything else uses the same fuse?

Any kind of work/replacement done than might have pinched a wire
underneath or shot a new screw threw a wire?

Some speaker systems run "hot leads" and do not behave well
if a lead gets grounded...

--
Leon Fisk
Grand Rapids MI

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"Leon Fisk" wrote in message
...
On Tue, 24 Sep 2019 07:58:47 -0500
Terry Coombs wrote:

When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply .
He
did tell me that the radio had "died" , turns out the fuse (in the
fuse
block) keeps blowing . I've got the dashboard apart enough to check
the
wiring harness and supply wires , can't find any cuts or anything
that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I
figured
it was the radio/CD player unit so I got a new one , does the same
thing
. I'm really puzzled by this , from the way the fuse was spattered
it's
got to be a dead short to ground . I think it very unlikely that the
new
radio/CD unit is bad - the old one did work when I replaced the fuse
,
for a few miles same as the new unit . This is an '86 GMC pickup ,
I'm
hoping someone here might be aware of a known problem area that I
might
check ... I gotta have tunes !


Just some random ideas... Does it have a power antenna? (doubtful)

Check the fuse schematic and see if anything else uses the same fuse?

Any kind of work/replacement done than might have pinched a wire
underneath or shot a new screw threw a wire?

Some speaker systems run "hot leads" and do not behave well
if a lead gets grounded...

--
Leon Fisk
Grand Rapids MI

=====================
Good suggestion.

I prioritize my troubleshooting sequence partly by how quick and easy
the tests are with available equipment. How would you check for an
intermittent speaker wire short to ground?






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On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !

It´s classic for sure. The power wire is bouncing around as you drive, and
over time the wire insulation was worn through, allowing contact between
copper wire and some part of the steel body.When you find the spot, it will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically prevent
further contact.

Joe Gwinn


Â* I kinda figure you're right , there's a place where it's worn thru .
The problem is finding that spot ... if it was obvious I'd have found it
by now . I've looked and felt as much of that harness as is available to
check , nothing so far . I'm starting to wonder if it's in/near the fuse
block , maybe where the under-dash wiring comes from behind the block .
But it's raining today , and I'll be too busy to look into it further
until Friday or Saturday .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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On 9/24/2019 9:04 AM, Jim Wilkins wrote:
"Terry Coombs" wrote in message
...
When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply .
He did tell me that the radio had "died" , turns out the fuse (in
the fuse block) keeps blowing . I've got the dashboard apart enough
to check the wiring harness and supply wires , can't find any cuts
or anything that looks like damaged insulation ... it works just
fine sittin' in the driveway , but within a few miles driving it
blows the fuse . I figured it was the radio/CD player unit so I got
a new one , does the same thing . I'm really puzzled by this , from
the way the fuse was spattered it's got to be a dead short to ground
. I think it very unlikely that the new radio/CD unit is bad - the
old one did work when I replaced the fuse , for a few miles same as
the new unit . This is an '86 GMC pickup , I'm hoping someone here
might be aware of a known problem area that I might check ... I
gotta have tunes !

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

Check/clean the battery connections.

If connector vibration momentarily disconnects the battery from the
charging circuit, the alternator output voltage will rise until a
protective clamping device somewhere, like in the radio, conducts
enough current to limit it. The voltage regulator tries to cut off the
alternator field current but can't remove the current already flowing
in the field winding.

https://en.wikipedia.org/wiki/Load_dump




Â* Wouldn't that blow the smaller fuse in the radio itself before the 15
amp supply fuse ?

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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On 9/24/2019 9:11 AM, Leon Fisk wrote:
On Tue, 24 Sep 2019 07:58:47 -0500
Terry Coombs wrote:

Â*Â* When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !

Just some random ideas... Does it have a power antenna? (doubtful)


Â* Nope , no power antenna .


Check the fuse schematic and see if anything else uses the same fuse?


Â* As far as I can tell it's only the radio , nothing else goes dead .


Any kind of work/replacement done than might have pinched a wire
underneath or shot a new screw threw a wire?


Â*Â* Nope , no other work besides a transmission replacement . I don't
think the power lead for the radio goes anywhere there .

Some speaker systems run "hot leads" and do not behave well
if a lead gets grounded...


Â* No powered speakers , basic stock 4 speaker system , I have some
bigger speakers in a box behind the seat . I've never had any problems
with the stereo system in the 12 years I've had this truck - until I
loaned it to my son "for a few weeks" that turned into a year and a half
.. In fact , the only problems I've had were normal wear-n-tear stuff
that happens with over 120k on the odometer .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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"Terry Coombs" wrote in message
...
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he
just
couldn't be bothered to fix . One thing is the radio power supply
. He
did tell me that the radio had "died" , turns out the fuse (in the
fuse
block) keeps blowing . I've got the dashboard apart enough to
check the
wiring harness and supply wires , can't find any cuts or anything
that
looks like damaged insulation ... it works just fine sittin' in
the
driveway , but within a few miles driving it blows the fuse . I
figured
it was the radio/CD player unit so I got a new one , does the same
thing
. I'm really puzzled by this , from the way the fuse was spattered
it's
got to be a dead short to ground . I think it very unlikely that
the new
radio/CD unit is bad - the old one did work when I replaced the
fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup ,
I'm
hoping someone here might be aware of a known problem area that I
might
check ... I gotta have tunes !

It´s classic for sure. The power wire is bouncing around as you
drive, and
over time the wire insulation was worn through, allowing contact
between
copper wire and some part of the steel body.When you find the spot,
it will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically
prevent
further contact.

Joe Gwinn


I kinda figure you're right , there's a place where it's worn thru
. The problem is finding that spot ... if it was obvious I'd have
found it by now . I've looked and felt as much of that harness as is
available to check , nothing so far . I'm starting to wonder if it's
in/near the fuse block , maybe where the under-dash wiring comes
from behind the block . But it's raining today , and I'll be too
busy to look into it further until Friday or Saturday .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !


Taping possible contact areas may help.

This has been useful when there are no voltage-sensitive components at
risk, like older appliances:
https://www.amazon.com/dp/B00975X2FY..._26725410_item

Battery-powered ones are more convenient, but don't stop generating if
you get shocked.


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"Terry Coombs" wrote in message
...
On 9/24/2019 9:04 AM, Jim Wilkins wrote:
"Terry Coombs" wrote in message
...
When I got my truck back from our son , lots of things that he
just
couldn't be bothered to fix . One thing is the radio power supply
.
He did tell me that the radio had "died" , turns out the fuse (in
the fuse block) keeps blowing . I've got the dashboard apart
enough
to check the wiring harness and supply wires , can't find any cuts
or anything that looks like damaged insulation ... it works just
fine sittin' in the driveway , but within a few miles driving it
blows the fuse . I figured it was the radio/CD player unit so I
got
a new one , does the same thing . I'm really puzzled by this ,
from
the way the fuse was spattered it's got to be a dead short to
ground
. I think it very unlikely that the new radio/CD unit is bad - the
old one did work when I replaced the fuse , for a few miles same
as
the new unit . This is an '86 GMC pickup , I'm hoping someone here
might be aware of a known problem area that I might check ... I
gotta have tunes !

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

Check/clean the battery connections.

If connector vibration momentarily disconnects the battery from the
charging circuit, the alternator output voltage will rise until a
protective clamping device somewhere, like in the radio, conducts
enough current to limit it. The voltage regulator tries to cut off
the
alternator field current but can't remove the current already
flowing
in the field winding.

https://en.wikipedia.org/wiki/Load_dump




Wouldn't that blow the smaller fuse in the radio itself before the
15 amp supply fuse ?

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !


Hard to say without looking. Some fuses blow immediately, others have
a time delay to allow high-current startup surges like charging the
power supply capacitors. For example I can pull 70A for about 10
seconds through the 30A output circuit breaker on my home brew 24V
battery charger.

Cleaning the battery connections is a good idea whether or not it
helps here.




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On 9/24/2019 10:07 AM, Jim Wilkins wrote:
"Terry Coombs" wrote in message
...
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he
just
couldn't be bothered to fix . One thing is the radio power supply
. He
did tell me that the radio had "died" , turns out the fuse (in the
fuse
block) keeps blowing . I've got the dashboard apart enough to
check the
wiring harness and supply wires , can't find any cuts or anything
that
looks like damaged insulation ... it works just fine sittin' in
the
driveway , but within a few miles driving it blows the fuse . I
figured
it was the radio/CD player unit so I got a new one , does the same
thing
. I'm really puzzled by this , from the way the fuse was spattered
it's
got to be a dead short to ground . I think it very unlikely that
the new
radio/CD unit is bad - the old one did work when I replaced the
fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup ,
I'm
hoping someone here might be aware of a known problem area that I
might
check ... I gotta have tunes !
It´s classic for sure. The power wire is bouncing around as you
drive, and
over time the wire insulation was worn through, allowing contact
between
copper wire and some part of the steel body.When you find the spot,
it will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically
prevent
further contact.

Joe Gwinn

I kinda figure you're right , there's a place where it's worn thru
. The problem is finding that spot ... if it was obvious I'd have
found it by now . I've looked and felt as much of that harness as is
available to check , nothing so far . I'm starting to wonder if it's
in/near the fuse block , maybe where the under-dash wiring comes
from behind the block . But it's raining today , and I'll be too
busy to look into it further until Friday or Saturday .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

Taping possible contact areas may help.

This has been useful when there are no voltage-sensitive components at
risk, like older appliances:
https://www.amazon.com/dp/B00975X2FY..._26725410_item

Battery-powered ones are more convenient, but don't stop generating if
you get shocked.



Â* And at a thousand volts ... someone else on another ng posted a link
to wiring diagrams , which led my eventually to a forum post that
indicates that power lead goes straight and only to the radio . It comes
out of the harness with the correct other wires . I have traced that
harness from the fuse block to the radio and find no damage or rubs or
torn wrap . My next step will be to pull the fuse block from the
firewall and check for problems on the back side . Gotta pull the plug
off from the rngine side first , and that ain't happenin' in the rain .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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"Terry Coombs" wrote in message
...
On 9/24/2019 10:07 AM, Jim Wilkins wrote:
"Terry Coombs" wrote in message
...
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he
just
couldn't be bothered to fix . One thing is the radio power
supply
. He
did tell me that the radio had "died" , turns out the fuse (in
the
fuse
block) keeps blowing . I've got the dashboard apart enough to
check the
wiring harness and supply wires , can't find any cuts or
anything
that
looks like damaged insulation ... it works just fine sittin' in
the
driveway , but within a few miles driving it blows the fuse . I
figured
it was the radio/CD player unit so I got a new one , does the
same
thing
. I'm really puzzled by this , from the way the fuse was
spattered
it's
got to be a dead short to ground . I think it very unlikely that
the new
radio/CD unit is bad - the old one did work when I replaced the
fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup
,
I'm
hoping someone here might be aware of a known problem area that
I
might
check ... I gotta have tunes !
It´s classic for sure. The power wire is bouncing around as you
drive, and
over time the wire insulation was worn through, allowing contact
between
copper wire and some part of the steel body.When you find the
spot,
it will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically
prevent
further contact.

Joe Gwinn

I kinda figure you're right , there's a place where it's worn
thru
. The problem is finding that spot ... if it was obvious I'd have
found it by now . I've looked and felt as much of that harness as
is
available to check , nothing so far . I'm starting to wonder if
it's
in/near the fuse block , maybe where the under-dash wiring comes
from behind the block . But it's raining today , and I'll be too
busy to look into it further until Friday or Saturday .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

Taping possible contact areas may help.

This has been useful when there are no voltage-sensitive components
at
risk, like older appliances:
https://www.amazon.com/dp/B00975X2FY..._26725410_item

Battery-powered ones are more convenient, but don't stop generating
if
you get shocked.



And at a thousand volts ... someone else on another ng posted a
link to wiring diagrams , which led my eventually to a forum post
that indicates that power lead goes straight and only to the radio .
It comes out of the harness with the correct other wires . I have
traced that harness from the fuse block to the radio and find no
damage or rubs or torn wrap . My next step will be to pull the fuse
block from the firewall and check for problems on the back side .
Gotta pull the plug off from the rngine side first , and that ain't
happenin' in the rain .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !


My truck sat idle for 3 years because I couldn't locate an
intermittent electrical fault, despite disassembling and cleaning all
the engine connectors and replacing most of the components. I finally
bought the factory engine and emission manual from Ebay and used it to
find the problem with an oscilloscope.

I hadn't replaced the ignition module because its mounting screws were
corroded in place. When it tested questionable and I did remove it one
broke and I had to make a drill jig to bore out the steel screw
without ruining the aluminum intake manifold's threads.


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On Tue, 24 Sep 2019 10:44:55 -0400
"Jim Wilkins" wrote:

snip
I prioritize my troubleshooting sequence partly by how quick and easy
the tests are with available equipment. How would you check for an
intermittent speaker wire short to ground?


Well Snag says it has four speakers. Maybe two in front and two in
back...

I would disconnect say the rear pair at the radio plug and see if it
still happens. If not try vice-versa...

When I was still working on radios years ago some speakers were tied
directly to DC voltage/amp circuit. No output transformer and no inline
capacitor. They had to be isolated from each other and ground or
trouble would ensue...

--
Leon Fisk
Grand Rapids MI

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Terry Coombs wrote:
When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !


The Yellow wire is the main power to the radio, fed by a 15 amp fuse.
Black is ground.

Disconnect the radio and go for a drive, see if the fuse fails. I think
it will as I suspect you have a short inside the harness. The easiest
fix would be to run a bypass wire from the fuse box to the radio.
If it was a constant short it would be easy to find, intermittent ones
can be a bear.

If you wish you can visit 2carpros.com and get the wiring diagrams, but
the system isn't complicated.

--
Steve W.
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"Leon Fisk" wrote in message
...
On Tue, 24 Sep 2019 10:44:55 -0400
"Jim Wilkins" wrote:

snip
I prioritize my troubleshooting sequence partly by how quick and
easy
the tests are with available equipment. How would you check for an
intermittent speaker wire short to ground?


Well Snag says it has four speakers. Maybe two in front and two in
back...

I would disconnect say the rear pair at the radio plug and see if it
still happens. If not try vice-versa...

When I was still working on radios years ago some speakers were tied
directly to DC voltage/amp circuit. No output transformer and no
inline
capacitor. They had to be isolated from each other and ground or
trouble would ensue...

--
Leon Fisk
Grand Rapids MI


My electronic experience is almost all industrial and military, very
little consumer. Was that an H bridge?




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"Steve W." wrote in message
...
Terry Coombs wrote:
When I got my truck back from our son , lots of things that he
just couldn't be bothered to fix . One thing is the radio power
supply . He did tell me that the radio had "died" , turns out the
fuse (in the fuse block) keeps blowing . I've got the dashboard
apart enough to check the wiring harness and supply wires , can't
find any cuts or anything that looks like damaged insulation ... it
works just fine sittin' in the driveway , but within a few miles
driving it blows the fuse . I figured it was the radio/CD player
unit so I got a new one , does the same thing . I'm really puzzled
by this , from the way the fuse was spattered it's got to be a dead
short to ground . I think it very unlikely that the new radio/CD
unit is bad - the old one did work when I replaced the fuse , for a
few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I
might check ... I gotta have tunes !


The Yellow wire is the main power to the radio, fed by a 15 amp
fuse.
Black is ground.

Disconnect the radio and go for a drive, see if the fuse fails. I
think it will as I suspect you have a short inside the harness. The
easiest fix would be to run a bypass wire from the fuse box to the
radio.
If it was a constant short it would be easy to find, intermittent
ones can be a bear.

If you wish you can visit 2carpros.com and get the wiring diagrams,
but the system isn't complicated.

--
Steve W.


Can you extend the fuse holder and install a fuse with an LED
indicator that could show you what driving conditions cause the fault?
https://www.picoauto.com/products/br...extension-lead


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On 9/24/2019 9:50 AM, Terry Coombs wrote:
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !

It´s classic for sure. The power wire is bouncing around as you drive,
and
over time the wire insulation was worn through, allowing contact between
copper wire and some part of the steel body.When you find the spot, it
will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically prevent
further contact.

Joe Gwinn


Â* I kinda figure you're right , there's a place where it's worn thru .
The problem is finding that spot ... if it was obvious I'd have found it
by now . I've looked and felt as much of that harness as is available to
check , nothing so far . I'm starting to wonder if it's in/near the fuse
block , maybe where the under-dash wiring comes from behind the block .
But it's raining today , and I'll be too busy to look into it further
until Friday or Saturday .


If you know where it comes out of the fuse block. cut it at about 8",
connect a new wire, run that up to the radio and do the same at the
other end. Give yourself 8" out of the radio connector and connect your
new wire.
Also, I would have taken the connector loose from the radio and drove
it before I got a new radio, just to verify, harness or radio.
Mikek
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On 9/24/2019 4:39 PM, Jim Wilkins wrote:
"Steve W." wrote in message
...
Terry Coombs wrote:
When I got my truck back from our son , lots of things that he
just couldn't be bothered to fix . One thing is the radio power
supply . He did tell me that the radio had "died" , turns out the
fuse (in the fuse block) keeps blowing . I've got the dashboard
apart enough to check the wiring harness and supply wires , can't
find any cuts or anything that looks like damaged insulation ... it
works just fine sittin' in the driveway , but within a few miles
driving it blows the fuse . I figured it was the radio/CD player
unit so I got a new one , does the same thing . I'm really puzzled
by this , from the way the fuse was spattered it's got to be a dead
short to ground . I think it very unlikely that the new radio/CD
unit is bad - the old one did work when I replaced the fuse , for a
few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I
might check ... I gotta have tunes !

The Yellow wire is the main power to the radio, fed by a 15 amp
fuse.
Black is ground.

Disconnect the radio and go for a drive, see if the fuse fails. I
think it will as I suspect you have a short inside the harness. The
easiest fix would be to run a bypass wire from the fuse box to the
radio.
If it was a constant short it would be easy to find, intermittent
ones can be a bear.

If you wish you can visit 2carpros.com and get the wiring diagrams,
but the system isn't complicated.

--
Steve W.

Can you extend the fuse holder and install a fuse with an LED
indicator that could show you what driving conditions cause the fault?
https://www.picoauto.com/products/br...extension-lead



Â* I'm thinking that Steve is right , it's inside the harness . I spent
over an hour today minutely inspecting that harness for any kind of
damage that might be the short . I'm tied up tomorrow and Thursday , but
on Friday I'll be pulling that fuse block and probably running a new
power supply wire outside the harness . As far as what conditions cause
the short , that's what is weird . I have over a mile of rough (ROUGH!)
unpaved road to get to the highway , the radio died a couple of miles
after I hit the paved road .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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On 9/24/2019 4:45 PM, amdx wrote:
On 9/24/2019 9:50 AM, Terry Coombs wrote:
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the
fuse
block) keeps blowing . I've got the dashboard apart enough to check
the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I
figured
it was the radio/CD player unit so I got a new one , does the same
thing
. I'm really puzzled by this , from the way the fuse was spattered
it's
got to be a dead short to ground . I think it very unlikely that
the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I
might
check ... I gotta have tunes !
It´s classic for sure. The power wire is bouncing around as you
drive, and
over time the wire insulation was worn through, allowing contact
between
copper wire and some part of the steel body.When you find the spot,
it will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically
prevent
further contact.

Joe Gwinn


Â*Â* I kinda figure you're right , there's a place where it's worn thru
. The problem is finding that spot ... if it was obvious I'd have
found it by now . I've looked and felt as much of that harness as is
available to check , nothing so far . I'm starting to wonder if it's
in/near the fuse block , maybe where the under-dash wiring comes from
behind the block . But it's raining today , and I'll be too busy to
look into it further until Friday or Saturday .


Â*If you know where it comes out of the fuse block. cut it at about 8",
connect a new wire, run that up to the radio and do the same at the
other end. Give yourself 8" out of the radio connector and connect
your new wire.
Â*Also, I would have taken the connector loose from the radio and drove
it before I got a new radio, just to verify, harness or radio.
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â* Mikek


Â* I wanted a new radio anyway ... that one was a freebie , the
back-light on the faceplate died some time ago and it has no aux inputs
.. As I mentioned here somewhere , I'll be looking into doing what you
suggest on Friday . Tied up until then .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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Default wires are metal ...

"Terry Coombs" wrote in message
...
...
I'm thinking that Steve is right , it's inside the harness . I
spent over an hour today minutely inspecting that harness for any
kind of damage that might be the short . I'm tied up tomorrow and
Thursday , but on Friday I'll be pulling that fuse block and
probably running a new power supply wire outside the harness . As
far as what conditions cause the short , that's what is weird . I
have over a mile of rough (ROUGH!) unpaved road to get to the
highway , the radio died a couple of miles after I hit the paved
road .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !


You might research how to make a reliable splice in vehicle wiring,
since vibrating copper wire tends to work-harden and break. When
engine electronics expanded in the 1970's even the engineers had
trouble with connections.

When I was wiring prototype electric vehicles the company had the
proper expensive crimping tools. Soldering is usually bad because it
can create a stress concentration where the wires exit the solder,
which hastens breakage. The motor in my Maytag washing machine failed
that way.

I don't have a 100% perfect record of crimp-splicing wires at home
with cheap consumer or worn industrial tooling and like welding it's a
muscle-memory type job I'm better at doing than describing.




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Default wires are metal ...

On Tue, 24 Sep 2019 07:58:47 -0500
Terry Coombs wrote:

huge snip
This is an '86 GMC pickup


Went and found a manual for same or similar online (64mb):

http://www.73-87chevytrucks.com/tech...ice_Manual.pdf

It seems that the fuse for the radio may also do a few other things:

Idle Stop Solenoid, Aux. Battery, Radio, Time Delay Relay, Emission
Control Solenoid, Transmission Downshift (M40) ..... 15 amp

This is from page 1331 in the manual mentioned above. Maybe it will
make more sense to Snag...

--
Leon Fisk
Grand Rapids MI

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On Tue, 24 Sep 2019 17:25:17 -0400
"Jim Wilkins" wrote:

snip
My electronic experience is almost all industrial and military, very
little consumer. Was that an H bridge?


Don't know Jim, just stuff I saw changing in the way things were
being done via schematics. I posted an image here of the power output
section, schematic for an old RS Cassette player in my truck:

https://i.postimg.cc/nhR9tKmK/RS-Cassette-Schem1.jpg

Note the voltage on the output IC's headed directly to the speakers...

--
Leon Fisk
Grand Rapids MI

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"Leon Fisk" wrote in message
...
On Tue, 24 Sep 2019 07:58:47 -0500
Terry Coombs wrote:

huge snip
This is an '86 GMC pickup


Went and found a manual for same or similar online (64mb):

http://www.73-87chevytrucks.com/tech...ice_Manual.pdf

It seems that the fuse for the radio may also do a few other things:

Idle Stop Solenoid, Aux. Battery, Radio, Time Delay Relay, Emission
Control Solenoid, Transmission Downshift (M40) ..... 15 amp

This is from page 1331 in the manual mentioned above. Maybe it will
make more sense to Snag...

--
Leon Fisk
Grand Rapids MI


I'm a big fan of monitoring current as well as voltage when hunting
for a problem, and I built analog and digital ammeters into my home
solar system.

https://www.ebay.com/itm/BLUE-POINT-...-/163252692497
It does read DC current, but it drifts and is noisy on a scope.


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On Wed, 25 Sep 2019 12:38:06 -0400
"Jim Wilkins" wrote:

snip
I'm a big fan of monitoring current as well as voltage when hunting
for a problem, and I built analog and digital ammeters into my home
solar system.

https://www.ebay.com/itm/BLUE-POINT-...-/163252692497
It does read DC current, but it drifts and is noisy on a scope.


I hear yah

I originally bought my Fluke 87 to try figuring out an intermittent
problem at a rural tower site. Base station was occasionally blow
a fuse. The 87 has MIN/MAX capture capabilities. It didn't work out
though, really need something with more inputs and logging abilities...

So I started moving an added inline fused lead around, see if it blew
or not. Turned out being a bad high voltage transformer, very expensive
and not something any of us had ever seen go bad before.

This was many years ago. The 87 hadn't been out long then. Nowadays
there are some pretty nice looking meters for not so much money that
would be great for stuff like that.

--
Leon Fisk
Grand Rapids MI

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"Leon Fisk" wrote in message
...
On Wed, 25 Sep 2019 12:38:06 -0400
"Jim Wilkins" wrote:

snip
I'm a big fan of monitoring current as well as voltage when hunting
for a problem, and I built analog and digital ammeters into my home
solar system.

https://www.ebay.com/itm/BLUE-POINT-...-/163252692497
It does read DC current, but it drifts and is noisy on a scope.


I hear yah

I originally bought my Fluke 87 to try figuring out an intermittent
problem at a rural tower site. Base station was occasionally blow
a fuse. The 87 has MIN/MAX capture capabilities. It didn't work out
though, really need something with more inputs and logging
abilities...

So I started moving an added inline fused lead around, see if it
blew
or not. Turned out being a bad high voltage transformer, very
expensive
and not something any of us had ever seen go bad before.

This was many years ago. The 87 hadn't been out long then. Nowadays
there are some pretty nice looking meters for not so much money that
would be great for stuff like that.

--
Leon Fisk
Grand Rapids MI


I use TP4000ZCs to datalog slowly changing voltages, temperatures and
currents on a laptop.
https://www.amazon.com/Tekpower-TP40.../dp/B000OPDFLM

The data outputs are optically isolated so the meters commons won't
short different voltages together. The TP4000ZC takes primary or
rechargeable AA cells and the laptop can operate at a remote site from
a jumpstarter battery and inverter or auto-air adapter. The older,
thicker laptops I use have PC Card and ExpressCard slots that take
extra COM or USB port expanders.

The setup is clumsier and slower than a good industrial datalogger but
much cheaper, and has the laptop's user interface and huge storage
capacity and the versatility of all the meters' input ranges.




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Default wires are metal ...

On Wed, 25 Sep 2019 07:34:49 -0400, "Jim Wilkins"
wrote:

"Terry Coombs" wrote in message
...
...
I'm thinking that Steve is right , it's inside the harness . I
spent over an hour today minutely inspecting that harness for any
kind of damage that might be the short . I'm tied up tomorrow and
Thursday , but on Friday I'll be pulling that fuse block and
probably running a new power supply wire outside the harness . As
far as what conditions cause the short , that's what is weird . I
have over a mile of rough (ROUGH!) unpaved road to get to the
highway , the radio died a couple of miles after I hit the paved
road .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !


You might research how to make a reliable splice in vehicle wiring,
since vibrating copper wire tends to work-harden and break. When
engine electronics expanded in the 1970's even the engineers had
trouble with connections.

When I was wiring prototype electric vehicles the company had the
proper expensive crimping tools. Soldering is usually bad because it
can create a stress concentration where the wires exit the solder,
which hastens breakage. The motor in my Maytag washing machine failed
that way.

I don't have a 100% perfect record of crimp-splicing wires at home
with cheap consumer or worn industrial tooling and like welding it's a
muscle-memory type job I'm better at doing than describing.

About the worst I ever ran across was a 1983 Dodge Aries where the
wiring harness for door locks and power windows complete with cloth
tape protected, spot welded branch connections, was routed under the
floor mat insulation/padding under the drivers feet. Were else in the
car could you find a greater quantity of chemical laden water during
cold weather in the Great White North!
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On Wed, 25 Sep 2019 10:03:32 -0400, Leon Fisk
wrote:

On Tue, 24 Sep 2019 07:58:47 -0500
Terry Coombs wrote:

huge snip
This is an '86 GMC pickup


Went and found a manual for same or similar online (64mb):

http://www.73-87chevytrucks.com/tech...ice_Manual.pdf

It seems that the fuse for the radio may also do a few other things:

Idle Stop Solenoid, Aux. Battery, Radio, Time Delay Relay, Emission
Control Solenoid, Transmission Downshift (M40) ..... 15 amp

This is from page 1331 in the manual mentioned above. Maybe it will
make more sense to Snag...

ANd the tranny WAS just changed - I'd definitely be looking at
downshift wire - - -
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Gerry wrote:
About the worst I ever ran across was a 1983 Dodge Aries where the
wiring harness for door locks and power windows complete with cloth
tape protected, spot welded branch connections, was routed under the
floor mat insulation/padding under the drivers feet. Were else in the
car could you find a greater quantity of chemical laden water during
cold weather in the Great White North!


Don't start looking at modern cars and trucks then. Wiring under the
carpet is nothing these days. Many locate the primary control modules
like the BCM or ECM under the carpets or even in pockets under the
floors. Many of these are domestics and the high dollar imports.
Mercedes locates various modules under the carpet and even in the
channels between the door and floor. I've opened up BMWs where the ECMs
are in a case below the floor that were full of water!

--
Steve W.
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On Wed, 25 Sep 2019 16:12:43 -0400
"Jim Wilkins" wrote:

snip
I use TP4000ZCs to datalog slowly changing voltages, temperatures and
currents on a laptop.
https://www.amazon.com/Tekpower-TP40.../dp/B000OPDFLM

The data outputs are optically isolated so the meters commons won't
short different voltages together. The TP4000ZC takes primary or
rechargeable AA cells and the laptop can operate at a remote site from
a jumpstarter battery and inverter or auto-air adapter. The older,
thicker laptops I use have PC Card and ExpressCard slots that take
extra COM or USB port expanders.

The setup is clumsier and slower than a good industrial datalogger but
much cheaper, and has the laptop's user interface and huge storage
capacity and the versatility of all the meters' input ranges.


Most every time you post a link to something like that I go have a
look-see

I think my Fluke 87 cost around $325 in the early 90's. I'll bet the
two meters would swap back and forth between their rubber armor
seamlessly...

I bought several used DVM's last winter than need some love. A B&K 2810
for parts or repair. I fried my 2810 around last December doing
something really stupid and I miss it. Also a Fluke 37 which looks like
an early 87 series functionally and a Fluke 8010A which I think needs
some serious switch cleaning/repair. Maybe I'll get the urge to fix
them this season ;-)

--
Leon Fisk
Grand Rapids MI

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On Wed, 25 Sep 2019 23:37:16 -0400
Clare Snyder wrote:

On Wed, 25 Sep 2019 10:03:32 -0400, Leon Fisk
wrote:

On Tue, 24 Sep 2019 07:58:47 -0500
Terry Coombs wrote:

huge snip

[...]

Went and found a manual for same or similar online (64mb):

http://www.73-87chevytrucks.com/tech...ice_Manual.pdf

It seems that the fuse for the radio may also do a few other things:

Idle Stop Solenoid, Aux. Battery, Radio, Time Delay Relay, Emission
Control Solenoid, Transmission Downshift (M40) ..... 15 amp

This is from page 1331 in the manual mentioned above. Maybe it will
make more sense to Snag...

ANd the tranny WAS just changed - I'd definitely be looking at
downshift wire - - -


Maybe, the M40 is the THM400 transmission. Those trucks also used the
700R4 and THM350 which wouldn't apply then. If he does have the M40
then he could check it by turning on the key and depressing the
gas pedal to the floor. See if it blows a good fuse. There was a
procedure for checking the downshift function in that manual...

--
Leon Fisk
Grand Rapids MI



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On 9/26/2019 7:36 AM, Leon Fisk wrote:
On Wed, 25 Sep 2019 23:37:16 -0400
Clare Snyder wrote:

On Wed, 25 Sep 2019 10:03:32 -0400, Leon Fisk
wrote:

On Tue, 24 Sep 2019 07:58:47 -0500
Terry Coombs wrote:

huge snip

[...]
Went and found a manual for same or similar online (64mb):

http://www.73-87chevytrucks.com/tech...ice_Manual.pdf

It seems that the fuse for the radio may also do a few other things:

Idle Stop Solenoid, Aux. Battery, Radio, Time Delay Relay, Emission
Control Solenoid, Transmission Downshift (M40) ..... 15 amp

This is from page 1331 in the manual mentioned above. Maybe it will
make more sense to Snag...

ANd the tranny WAS just changed - I'd definitely be looking at
downshift wire - - -

Maybe, the M40 is the THM400 transmission. Those trucks also used the
700R4 and THM350 which wouldn't apply then. If he does have the M40
then he could check it by turning on the key and depressing the
gas pedal to the floor. See if it blows a good fuse. There was a
procedure for checking the downshift function in that manual...

Â* This truck has a 700R4 ... I'll be pulling that fuse block tomorrow
to see what's also hooked to that fuse - I'll also be checking those
diagrams that Leon posted the links to . Lots of good leads from y'all ,
I've been to Memphis to take the grandson home from his 2 week visit .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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On Tuesday, September 24, 2019 at 5:45:32 PM UTC-4, amdx wrote:
On 9/24/2019 9:50 AM, Terry Coombs wrote:
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !
It´s classic for sure. The power wire is bouncing around as you drive,
and
over time the wire insulation was worn through, allowing contact between
copper wire and some part of the steel body.When you find the spot, it
will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically prevent
further contact.

Joe Gwinn


Â* I kinda figure you're right , there's a place where it's worn thru .
The problem is finding that spot ... if it was obvious I'd have found it
by now . I've looked and felt as much of that harness as is available to
check , nothing so far . I'm starting to wonder if it's in/near the fuse
block , maybe where the under-dash wiring comes from behind the block .
But it's raining today , and I'll be too busy to look into it further
until Friday or Saturday .


If you know where it comes out of the fuse block. cut it at about 8",
connect a new wire, run that up to the radio and do the same at the
other end. Give yourself 8" out of the radio connector and connect your
new wire.
Also, I would have taken the connector loose from the radio and drove
it before I got a new radio, just to verify, harness or radio.
Mikek


Good plan, but... After cutting the wire a few inches out of the fuse block, I'd drive a few miles to make sure it doesn't blow the fuse. There's got to be some version of Murphy's Law that says the short will be in the wire you didn't check separately.

Also, a multimeter with a continuity beeper could be a friend here. Hook it up between the supply wire and ground (fuse pulled first) and then wiggle all the wires. When it beeps, you've found your short.
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On 9/28/2019 9:15 AM, rangerssuck wrote:
On Tuesday, September 24, 2019 at 5:45:32 PM UTC-4, amdx wrote:
On 9/24/2019 9:50 AM, Terry Coombs wrote:
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !
It´s classic for sure. The power wire is bouncing around as you drive,
and
over time the wire insulation was worn through, allowing contact between
copper wire and some part of the steel body.When you find the spot, it
will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically prevent
further contact.

Joe Gwinn


Â* I kinda figure you're right , there's a place where it's worn thru .
The problem is finding that spot ... if it was obvious I'd have found it
by now . I've looked and felt as much of that harness as is available to
check , nothing so far . I'm starting to wonder if it's in/near the fuse
block , maybe where the under-dash wiring comes from behind the block
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On Sat, 28 Sep 2019 14:58:24 -0500, gray_wolf
wrote:

On 9/28/2019 9:15 AM, rangerssuck wrote:
On Tuesday, September 24, 2019 at 5:45:32 PM UTC-4, amdx wrote:
On 9/24/2019 9:50 AM, Terry Coombs wrote:
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !
It´s classic for sure. The power wire is bouncing around as you drive,
and
over time the wire insulation was worn through, allowing contact between
copper wire and some part of the steel body.When you find the spot, it
will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically prevent
further contact.

Joe Gwinn


* I kinda figure you're right , there's a place where it's worn thru .
The problem is finding that spot ... if it was obvious I'd have found it
by now . I've looked and felt as much of that harness as is available to
check , nothing so far . I'm starting to wonder if it's in/near the fuse
block , maybe where the under-dash wiring comes from behind the block .
But it's raining today , and I'll be too busy to look into it further
until Friday or Saturday .


If you know where it comes out of the fuse block. cut it at about 8",
connect a new wire, run that up to the radio and do the same at the
other end. Give yourself 8" out of the radio connector and connect your
new wire.
Also, I would have taken the connector loose from the radio and drove
it before I got a new radio, just to verify, harness or radio.
Mikek


Good plan, but... After cutting the wire a few inches out of the fuse block, I'd drive a few miles to make sure it doesn't blow the fuse. There's got to be some version of Murphy's Law that says the short will be in the wire you didn't check separately.

Also, a multimeter with a continuity beeper could be a friend here. Hook it up between the supply wire and ground (fuse pulled first) and then wiggle all the wires. When it beeps, you've found your short.


Is the radio the only thing that's on that fuse? I'd run a new wire with an
inline fuse from the radio to the battery and see what happens. Are you sure the
problem isn't in the radio?

As noted on another group the trasnmission torqueconverter lockup
runs off that fuse too. Since the transmission swap was a "shade tree
job" the chances of it being related to the transmission replacement
are roughly 1000% - - - - - - - When the controls call for TC lockup
the fuse blows.
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"Clare Snyder" wrote in message
...

As noted on another group the trasnmission torqueconverter lockup
runs off that fuse too. Since the transmission swap was a "shade
tree
job" the chances of it being related to the transmission replacement
are roughly 1000% - - - - - - - When the controls call for TC lockup
the fuse blows.


On my Honda the TC lockup occurs only in the highest gears, at
constant speed on a level road, an easy condition to test with the
radio unplugged. I can tell when it's locked because the speedo and
tach needles move together.




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On 9/28/2019 3:34 PM, Clare Snyder wrote:
On Sat, 28 Sep 2019 14:58:24 -0500, gray_wolf
wrote:

On 9/28/2019 9:15 AM, rangerssuck wrote:
On Tuesday, September 24, 2019 at 5:45:32 PM UTC-4, amdx wrote:
On 9/24/2019 9:50 AM, Terry Coombs wrote:
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !
It´s classic for sure. The power wire is bouncing around as you drive,
and
over time the wire insulation was worn through, allowing contact between
copper wire and some part of the steel body.When you find the spot, it
will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically prevent
further contact.

Joe Gwinn

Â* I kinda figure you're right , there's a place where it's worn thru .
The problem is finding that spot ... if it was obvious I'd have found it
by now . I've looked and felt as much of that harness as is available to
check , nothing so far . I'm starting to wonder if it's in/near the fuse
block , maybe where the under-dash wiring comes from behind the block .
But it's raining today , and I'll be too busy to look into it further
until Friday or Saturday .

If you know where it comes out of the fuse block. cut it at about 8",
connect a new wire, run that up to the radio and do the same at the
other end. Give yourself 8" out of the radio connector and connect your
new wire.
Also, I would have taken the connector loose from the radio and drove
it before I got a new radio, just to verify, harness or radio.
Mikek
Good plan, but... After cutting the wire a few inches out of the fuse block, I'd drive a few miles to make sure it doesn't blow the fuse. There's got to be some version of Murphy's Law that says the short will be in the wire you didn't check separately.

Also, a multimeter with a continuity beeper could be a friend here. Hook it up between the supply wire and ground (fuse pulled first) and then wiggle all the wires. When it beeps, you've found your short.

Is the radio the only thing that's on that fuse? I'd run a new wire with an
inline fuse from the radio to the battery and see what happens. Are you sure the
problem isn't in the radio?

As noted on another group the trasnmission torqueconverter lockup
runs off that fuse too. Since the transmission swap was a "shade tree
job" the chances of it being related to the transmission replacement
are roughly 1000% - - - - - - - When the controls call for TC lockup
the fuse blows.


Â* And Clare found it , and I just a few minutes ago verified that this
is (with 99.99% assurance) the problem . I'll get under there tomorrow
and find where it's grounding , but I did a road test with speeds high
enough to call for lockup with that wire unplugged and the fuse is still
intact . The internet truly is an information highway . I would never
have known that device was powered by the same fuse as the radio .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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Default wires are metal ...

On 9/28/2019 4:27 PM, Terry Coombs wrote:
On 9/28/2019 3:34 PM, Clare Snyder wrote:
On Sat, 28 Sep 2019 14:58:24 -0500, gray_wolf
wrote:

On 9/28/2019 9:15 AM, rangerssuck wrote:
On Tuesday, September 24, 2019 at 5:45:32 PM UTC-4, amdx wrote:
On 9/24/2019 9:50 AM, Terry Coombs wrote:
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !
It´s classic for sure. The power wire is bouncing around as you drive,
and
over time the wire insulation was worn through, allowing contact between
copper wire and some part of the steel body.When you find the spot, it
will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically prevent
further contact.

Joe Gwinn

Â*Â* Â* I kinda figure you're right , there's a place where it's worn thru .
The problem is finding that spot ... if it was obvious I'd have found it
by now . I've looked and felt as much of that harness as is available to
check , nothing so far . I'm starting to wonder if it's in/near the fuse
block , maybe where the under-dash wiring comes from behind the block .
But it's raining today , and I'll be too busy to look into it further
until Friday or Saturday .

Â*Â*Â* If you know where it comes out of the fuse block. cut it at about 8",
connect a new wire, run that up to the radio and do the same at the
other end. Give yourself 8" out of the radio connector and connect your
new wire.
Â*Â*Â* Also, I would have taken the connector loose from the radio and drove
it before I got a new radio, just to verify, harness or radio.
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â*Â*Â*Â* Mikek
Good plan, but... After cutting the wire a few inches out of the fuse block,
I'd drive a few miles to make sure it doesn't blow the fuse. There's got to
be some version of Murphy's Law that says the short will be in the wire you
didn't check separately.

Also, a multimeter with a continuity beeper could be a friend here. Hook it
up between the supply wire and ground (fuse pulled first) and then wiggle
all the wires. When it beeps, you've found your short.

Is the radio the only thing that's on that fuse? I'd run a new wire with an
inline fuse from the radio to the battery and see what happens. Are you sure the
problem isn't in the radio?

Â* As noted on another group the trasnmission torqueconverter lockup
runs off that fuse too. Since the transmission swap was a "shade tree
job" the chances of it being related to the transmission replacement
are roughly 1000% - - - - - - - When the controls call for TC lockup
the fuse blows.


Â* And Clare found it , and I just a few minutes ago verified that this is (with
99.99% assurance) the problem . I'll get under there tomorrow and find where
it's grounding , but I did a road test with speeds high enough to call for
lockup with that wire unplugged and the fuse is still intact . The internet
truly is an information highway . I would never have known that device was
powered by the same fuse as the radio .


There are times when having a complete wiring diagram can be a big help. :-)
What's on the load side of the TC lockup output A solenoid or some such? shorted?


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Default wires are metal ...

On 9/28/2019 6:39 PM, gray_wolf wrote:
On 9/28/2019 4:27 PM, Terry Coombs wrote:
On 9/28/2019 3:34 PM, Clare Snyder wrote:
On Sat, 28 Sep 2019 14:58:24 -0500, gray_wolf
wrote:

On 9/28/2019 9:15 AM, rangerssuck wrote:
On Tuesday, September 24, 2019 at 5:45:32 PM UTC-4, amdx wrote:
On 9/24/2019 9:50 AM, Terry Coombs wrote:
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he
just
couldn't be bothered to fix . One thing is the radio power
supply . He
did tell me that the radio had "died" , turns out the fuse (in
the fuse
block) keeps blowing . I've got the dashboard apart enough to
check the
wiring harness and supply wires , can't find any cuts or
anything that
looks like damaged insulation ... it works just fine sittin'
in the
driveway , but within a few miles driving it blows the fuse .
I figured
it was the radio/CD player unit so I got a new one , does the
same thing
. I'm really puzzled by this , from the way the fuse was
spattered it's
got to be a dead short to ground . I think it very unlikely
that the new
radio/CD unit is bad - the old one did work when I replaced
the fuse ,
for a few miles same as the new unit . This is an '86 GMC
pickup , I'm
hoping someone here might be aware of a known problem area
that I might
check ... I gotta have tunes !
It´s classic for sure. The power wire is bouncing around as you
drive,
and
over time the wire insulation was worn through, allowing
contact between
copper wire and some part of the steel body.When you find the
spot, it
will
be pretty obvious visually.

Solution is to find out where this is happening, and
mechanically prevent
further contact.

Joe Gwinn

Â*Â* Â* I kinda figure you're right , there's a place where it's
worn thru .
The problem is finding that spot ... if it was obvious I'd have
found it
by now . I've looked and felt as much of that harness as is
available to
check , nothing so far . I'm starting to wonder if it's in/near
the fuse
block , maybe where the under-dash wiring comes from behind the
block .
But it's raining today , and I'll be too busy to look into it
further
until Friday or Saturday .

Â*Â*Â* If you know where it comes out of the fuse block. cut it at
about 8",
connect a new wire, run that up to the radio and do the same at the
other end. Give yourself 8" out of the radio connector and
connect your
new wire.
Â*Â*Â* Also, I would have taken the connector loose from the radio
and drove
it before I got a new radio, just to verify, harness or radio.
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â*Â*Â*Â* Mikek
Good plan, but... After cutting the wire a few inches out of the
fuse block, I'd drive a few miles to make sure it doesn't blow the
fuse. There's got to be some version of Murphy's Law that says the
short will be in the wire you didn't check separately.

Also, a multimeter with a continuity beeper could be a friend
here. Hook it up between the supply wire and ground (fuse pulled
first) and then wiggle all the wires. When it beeps, you've found
your short.

Is the radio the only thing that's on that fuse? I'd run a new wire
with an
inline fuse from the radio to the battery and see what happens. Are
you sure the
problem isn't in the radio?
Â* As noted on another group the trasnmission torqueconverter lockup
runs off that fuse too. Since the transmission swap was a "shade tree
job" the chances of it being related to the transmission replacement
are roughly 1000% - - - - - - - When the controls call for TC lockup
the fuse blows.


Â*Â* And Clare found it , and I just a few minutes ago verified that
this is (with 99.99% assurance) the problem . I'll get under there
tomorrow and find where it's grounding , but I did a road test with
speeds high enough to call for lockup with that wire unplugged and
the fuse is still intact . The internet truly is an information
highway . I would never have known that device was powered by the
same fuse as the radio .


There are times when having a complete wiring diagram can be a big
help. :-)
What's on the load side of the TC lockup outputÂ* A solenoid or some
such? shorted?



Â* Well , so far I have traced the brown/white wire across the steering
column to where it plugs in to a device - probably a relay of some kind
- mounted on the steering column . It comes out on a blue which goes
thru the firewall alone then to a small bundle that heads towards the
tranny . My guess is that the blue wire plugs (or is supposed to) into
the lockup solenoid , and is either unhooked or damaged and grounded .
I'll find out in the morning . My wife has resigned herself to me
keeping this truck , but that don't mean she's happy about it . I've
also got a set of 3.42:1 gears for the rear axle , the 2.73's just don't
get it up here in the "mountains" - I grew up in the "real" mountains ,
northern Utahaha at the foot of the Wasatch Front .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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Posts: 4,564
Default wires are metal ...

On Sat, 28 Sep 2019 18:39:40 -0500, gray_wolf
wrote:

On 9/28/2019 4:27 PM, Terry Coombs wrote:
On 9/28/2019 3:34 PM, Clare Snyder wrote:
On Sat, 28 Sep 2019 14:58:24 -0500, gray_wolf
wrote:

On 9/28/2019 9:15 AM, rangerssuck wrote:
On Tuesday, September 24, 2019 at 5:45:32 PM UTC-4, amdx wrote:
On 9/24/2019 9:50 AM, Terry Coombs wrote:
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !
It´s classic for sure. The power wire is bouncing around as you drive,
and
over time the wire insulation was worn through, allowing contact between
copper wire and some part of the steel body.When you find the spot, it
will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically prevent
further contact.

Joe Gwinn

** * I kinda figure you're right , there's a place where it's worn thru .
The problem is finding that spot ... if it was obvious I'd have found it
by now . I've looked and felt as much of that harness as is available to
check , nothing so far . I'm starting to wonder if it's in/near the fuse
block , maybe where the under-dash wiring comes from behind the block .
But it's raining today , and I'll be too busy to look into it further
until Friday or Saturday .

*** If you know where it comes out of the fuse block. cut it at about 8",
connect a new wire, run that up to the radio and do the same at the
other end. Give yourself 8" out of the radio connector and connect your
new wire.
*** Also, I would have taken the connector loose from the radio and drove
it before I got a new radio, just to verify, harness or radio.
***************************** Mikek
Good plan, but... After cutting the wire a few inches out of the fuse block,
I'd drive a few miles to make sure it doesn't blow the fuse. There's got to
be some version of Murphy's Law that says the short will be in the wire you
didn't check separately.

Also, a multimeter with a continuity beeper could be a friend here. Hook it
up between the supply wire and ground (fuse pulled first) and then wiggle
all the wires. When it beeps, you've found your short.

Is the radio the only thing that's on that fuse? I'd run a new wire with an
inline fuse from the radio to the battery and see what happens. Are you sure the
problem isn't in the radio?
* As noted on another group the trasnmission torqueconverter lockup
runs off that fuse too. Since the transmission swap was a "shade tree
job" the chances of it being related to the transmission replacement
are roughly 1000% - - - - - - - When the controls call for TC lockup
the fuse blows.


* And Clare found it , and I just a few minutes ago verified that this is (with
99.99% assurance) the problem . I'll get under there tomorrow and find where
it's grounding , but I did a road test with speeds high enough to call for
lockup with that wire unplugged and the fuse is still intact . The internet
truly is an information highway . I would never have known that device was
powered by the same fuse as the radio .


There are times when having a complete wiring diagram can be a big help. :-)
What's on the load side of the TC lockup output A solenoid or some such? shorted?

POSSIBLY a shorted solenoid valve - but most likely a pinched wire
from the transmission changeover. - possibly even just the wires
crossed sothe power goes directly to ground instead of through the
solenoid coil. You'd be surprised at what a shade tree mechanic is
capable of screwing up. (and I've seen some real "shade tree"
mechanics working in real shops too - - - - - )

Had one guy collect a paycheck from me for a couple months before I
had to let him go. Saying he "worked for me" would have been
stretching the truth. I'd bend over and put the knuckle of my thumb
against the ground and say "that's Dave". So lazy he was always
standing around with his thumb uph his arse - and so dumb he didn't
know his arse from a hole inthe ground. It took longer to clear up his
comebacks than the length of time he "worked for" me.
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Default wires are metal ...

On 9/28/2019 8:04 PM, Clare Snyder wrote:
On Sat, 28 Sep 2019 18:39:40 -0500, gray_wolf
wrote:

On 9/28/2019 4:27 PM, Terry Coombs wrote:
On 9/28/2019 3:34 PM, Clare Snyder wrote:
On Sat, 28 Sep 2019 14:58:24 -0500, gray_wolf
wrote:

On 9/28/2019 9:15 AM, rangerssuck wrote:
On Tuesday, September 24, 2019 at 5:45:32 PM UTC-4, amdx wrote:
On 9/24/2019 9:50 AM, Terry Coombs wrote:
On 9/24/2019 9:03 AM, Joseph Gwinn wrote:
On Sep 24, 2019, Terry Coombs wrote
(in article ):

When I got my truck back from our son , lots of things that he just
couldn't be bothered to fix . One thing is the radio power supply . He
did tell me that the radio had "died" , turns out the fuse (in the fuse
block) keeps blowing . I've got the dashboard apart enough to check the
wiring harness and supply wires , can't find any cuts or anything that
looks like damaged insulation ... it works just fine sittin' in the
driveway , but within a few miles driving it blows the fuse . I figured
it was the radio/CD player unit so I got a new one , does the same thing
. I'm really puzzled by this , from the way the fuse was spattered it's
got to be a dead short to ground . I think it very unlikely that the new
radio/CD unit is bad - the old one did work when I replaced the fuse ,
for a few miles same as the new unit . This is an '86 GMC pickup , I'm
hoping someone here might be aware of a known problem area that I might
check ... I gotta have tunes !
It´s classic for sure. The power wire is bouncing around as you drive,
and
over time the wire insulation was worn through, allowing contact between
copper wire and some part of the steel body.When you find the spot, it
will
be pretty obvious visually.

Solution is to find out where this is happening, and mechanically prevent
further contact.

Joe Gwinn

Â*Â* Â* I kinda figure you're right , there's a place where it's worn thru .
The problem is finding that spot ... if it was obvious I'd have found it
by now . I've looked and felt as much of that harness as is available to
check , nothing so far . I'm starting to wonder if it's in/near the fuse
block , maybe where the under-dash wiring comes from behind the block .
But it's raining today , and I'll be too busy to look into it further
until Friday or Saturday .

Â*Â*Â* If you know where it comes out of the fuse block. cut it at about 8",
connect a new wire, run that up to the radio and do the same at the
other end. Give yourself 8" out of the radio connector and connect your
new wire.
Â*Â*Â* Also, I would have taken the connector loose from the radio and drove
it before I got a new radio, just to verify, harness or radio.
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â*Â*Â*Â* Mikek
Good plan, but... After cutting the wire a few inches out of the fuse block,
I'd drive a few miles to make sure it doesn't blow the fuse. There's got to
be some version of Murphy's Law that says the short will be in the wire you
didn't check separately.

Also, a multimeter with a continuity beeper could be a friend here. Hook it
up between the supply wire and ground (fuse pulled first) and then wiggle
all the wires. When it beeps, you've found your short.

Is the radio the only thing that's on that fuse? I'd run a new wire with an
inline fuse from the radio to the battery and see what happens. Are you sure the
problem isn't in the radio?
Â* As noted on another group the trasnmission torqueconverter lockup
runs off that fuse too. Since the transmission swap was a "shade tree
job" the chances of it being related to the transmission replacement
are roughly 1000% - - - - - - - When the controls call for TC lockup
the fuse blows.

Â* And Clare found it , and I just a few minutes ago verified that this is (with
99.99% assurance) the problem . I'll get under there tomorrow and find where
it's grounding , but I did a road test with speeds high enough to call for
lockup with that wire unplugged and the fuse is still intact . The internet
truly is an information highway . I would never have known that device was
powered by the same fuse as the radio .


There are times when having a complete wiring diagram can be a big help. :-)
What's on the load side of the TC lockup output A solenoid or some such? shorted?

POSSIBLY a shorted solenoid valve - but most likely a pinched wire
from the transmission changeover. - possibly even just the wires
crossed sothe power goes directly to ground instead of through the
solenoid coil. You'd be surprised at what a shade tree mechanic is
capable of screwing up. (and I've seen some real "shade tree"
mechanics working in real shops too - - - - - )

Had one guy collect a paycheck from me for a couple months before I
had to let him go. Saying he "worked for me" would have been
stretching the truth. I'd bend over and put the knuckle of my thumb
against the ground and say "that's Dave". So lazy he was always
standing around with his thumb uph his arse - and so dumb he didn't
know his arse from a hole inthe ground. It took longer to clear up his
comebacks than the length of time he "worked for" me.



I know the feeling. In a past life I was the service manager of a large company.
good help was hard to find and I was well aware of some peoples limitations.
Lack of education? How do you educate a brick?



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