Help needed from anybody who's been down Electrical Troubleshooting
Expressway on the way to the nuthouse!
My '89 5.0 Crown Vic keeps blowing the 15 amp fuse that oversees the
brake/four way flasher circuit. It seems
to happen after a rainstorm or washing it in the driveway. Lens areas seem
to be dry so I don't think water is getting
into the housing. Ex police car with lots of aux "junk" and mods. (stripped
off) so might be one for the shop?
Thanks for any advice and experiences.
This might be a longshot... I'm an electrician, not an auto specialist.
A while back I was "helping" a friend troubleshoot a similar problem- the
dreaded intermittant short. After a LOT of wasted effort we decided to do a
really thorough procedure wherein we installed the fuse, and one-by-one
activated the different systems of the vehicle. By systems, I refer to
anything electrical, including fans, power windows, brake lights, flashers,
turn signals, etc. You get the idea.
Anyway, the problem was actually traced to a dangling wire under the dash.
Well... more likely under the windshield portion of the dash. I mean
WAAAAAYYY up in the top of the underneath we found a wire that someone had
previously cut and taped the end. After a while the tape fell off and the
end was exposed. When we grounded the end, it sparked and blew the 20 amp
fuse. Voila! The cause was found. We traced the wire to a junction where
it had been spliced into this circuit and removed it. Never did figure out
what the wire was added for.
How did we finally find it. We eliminated EVERY other system first, and
then traced the entire remaining circuit wire by wire. Knew this was going
to be a tough trace, so that's why we eliminated every other system first.
Now, none of this may help you in the slightest, but your problem just
jogged this incident back into my memory.
One more thought- Could the wiper arms be hitting something. You said when
it rains or you wash the car. Sometimes we run the wipers a cycle or two
when we wash our cars.
well could have had "blackout" installed. The installer will cut one of the
wires going to the switch and install an extra two wires going to a remote
switch to kill the brake lights. It could be that all the equipment was
removed and you have a short to ground in this extra wire. If this was done
to this car it will be obvious by the extra wires near the brake switch.
Just cut them out and re-connect the originals.
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