We just purchased a used 1997 F150 and after driving a few miles, the dash lights, tail lights, parking lights and license plates lights went out. We tried replacing the fuses and that didn't correct the problem (the fuses that were replaced all looked ok, but we replaced them anyway - also, we discovered 20 amp fuses were being used for 5 amp fuses).

Does anyone have any suggestions?

 

If they were using 20 amperes instead of 5's it tells me that it had an intermittant short somewhere that instead of fixing it right they stuck in bigger fuses. You have a short somewhere that burned up and caused an open in the circuit. Your going to need a wiring diagram to see if there are any fusible links in the circuit. If not you will need to trace the entire circuit with a test light to track down the problem.

Have fun, electrical problems suck!

-Jon

 

if it does not have trailer package i would start there at the hitch area

 

Hi gatr

Yeah, take it back to previous owner/lot...ask about it? Its an obvious problem that someone tried to fix by putting in bigger fuses. Bigger fuse can lead to bigger problems.

Anyhow...as posted...If fuses keep blowing, may have to start running circuit/load tests etc. Check obvious first....

Look for aftermarket elect. add ons and how their wired in...either still there or maybe you can see where something was removed. Look closely inside cab, under dash, outside and underneath cab/bed. Looking for loose bare/dangling wires etc...odd looking tape jobs to wiring harnesses etc. Maybe you'll get lucky, easy fix?

Good luck...OT

 

If the previous owner did any homebrew work on the truck (like installing a hookup for trailer lights, car stereo stuff, etc) I would take a good hard look at that too.

Mike

 

Please let me know what the cause was.
I just bought a '92 F250 Diesel, and it started doing the same thing.
Thanks
Jim

 

Does this vehicle have fog lights?
Trailer hitch? How many wires are on the trailer harness, 4 or 7?

JMC

 

Hi, JMC,
No fog lights, and I've disconnected the trailer/5th wheel connections, and the problem continues.

I replaced the light switch this morning, but I have not
tested yet - - - ran out of fuses....:-)

I think the problem will be the headlight switch, turn signal switch, or the wiring. The same circuits supplied by the blown fuse work when I set the headlight switch to a spot between
its 2 intended positions(running lights/running & headlights).

Gonna get somemore fuses and retest.
Thanks
Jim