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.