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 !