"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