Electrical gremlin

[malihoochie]

I am at wits end trying to find the electrical gremlin that is causing the fuse to blow everytime I turn on the headlights in my 1996 C1500 pickup truck. First off - the truck has 154,000 miles on it and this problem just popped up. The lights get turned on and it is any bodys guess how many seconds (or a few times, minutes) until the fuse blows with a startling SNAP! Sometimes it seems fine and as I pull out of the driveway it blows the fuse and the dash lights and tail lights are gone. Brake lights & blinkers work fine. Ideas?

[malihoochie]

As the days are getting shorter this is becoming a big concern, having to drive home at dusk.
Thanks in advance for any help.

[MrQuick]

I've seen my share of bulbs causing shorts these days. Try disconnecting the headlight bulbs till your short goes away...You can use a volt meter,test light or make a short tester out of a bulb and some wire to test for shorts instead of wasting fuses.

[6'9"Witha69]

Also, tracing shorts can be easier when looking at the ends where the wires are most exposed. It is seldom that they occur within the harness. More often they are where the wires come out of the harness and can chaff on surrounding parts.

[malihoochie]

I was told that often the headlight switch goes bad and could cause the issue I am having. I replaced the switch and it was no different. $40 wasted. I traced as much of the wiring harness as I could and checked as much as I could with a test light - no cause of the problem was found. Arrgg! I hate to even think of just throwing $$ at stuff in hopes of getting lucky and hitting the culprit, but I did just that after multiple people told me the bright/turn signal/wiper switch is a part notorious for failing and making problems like mine. I bit the bullet and bought this stupid switch - and $200 was shot as well - not the gremlin I was after.

[Josh]

Did you try the bulbs?

[malihoochie]

I did check (most ?) of them in the tail lights when this initially started. I was looking mostly for burnt bulbs, none were loose though. The bulbs are the flat style, not twist in. And the panel that the bulbs go into has a circuit style of connection to the actual wire harness. I will check the tail & headlight bulbs asap. Damn this is frustrating!

[malihoochie]

As I type this I have the grill off and the tail lights out. Earlier I unhooked the rear lights completely and turned on the lights. Pop! Fuse blows. Unhooked a painless wiring add-on piece that turns on all 4 lights when you hit the brights (this has been on the truck for about 6 years, it is not a new add-on/obvious culprit). New fuse in - turned on the lights ... Pow! Grrrrr! pulled the drivers side low beam headlight wiring and tried the lights again... pop! Pulled the grill so I could get to the high beam bulb wiring, and all the other running light/turn signal bulbs and connections. I pulled out all the drivers side bulbs looked them over - gave them all the evil eye, and with the lights on (fuse is holding strong..) installed them one by one. No fuse failure. Tried the brights, turn signals, shook any wires I could reach, repeatedly opened and shut the door, put the truck in reverse/drive and drove a few feet either way. Fuse is holding up. Switch was turned on off, on off, no "pop". I would rejoice but I'm afraid it is a ruse designed to get me in the midst of a test ride - only to blow again. The only change I actually made to anything is wiping off a little bit of the factory grease from the turn signal bulb bases on the drivers side. I cannot seem to find anything wrong and also (so far) cannot get the failing fuse to repeat. Any ideas? Think I blew $$$ only to need to wipe a bit of factory installed grease off of a couple amber bulbs? I'll go continue trying it and check back in a while to see if anyone has any ideas, and tell what I find out.

[6'9"Witha69]

Sounds like moving the wiring around may have removed a short.

[malihoochie]

It has been working so far (since last night), but I don't really know why. Maybe pulling on and shaking areas of the harness was the cure, but I never found an obvious cause. I hope I shook the hell outta that short, and that it never returns. I've never "fixed" anything this way before, LOL.

[6'9"Witha69]

I hope I shook the hell outta that short, and that it never returns. I've never "fixed" anything this way before, LOL.

I used to have a short in the headlight switch wiring that I "fixed" every couple weeks by reaching under the dash and shaking the harness (it was a DD in college and I was too busy making it fast to care about it). The short actually wouldn't allow the engine to stop until the headlights were turned off.

Problem is, wiring sets up over time and heat cycles, so it will likely fall back to where it was and potentially short again (or not, hopefully).

[MonzaRacer]

put a circuit breaker in till it actually starts making some smoke.

[CamaroAJ]

put a circuit breaker in till it actually starts making some smoke.

lol, i did that once to a truck under warranty that the customer had some super power sucker lights on and i had to put a whole dash harness in it because it was smoking and shorted wires together. the customer was putting 30A fuses in a 10A circuit and started the problem and that 10A circuit braker finished it haha.

back on topic......check for poor grounds as well as they can cause a fuse to blow. i don't remember off the top of my head but didn't 96 trucks have a DRL module? i seem to remember replacing a few of those.

[malihoochie]

The truck SHOULD have day time running lights and used to...but they just stopped working after time & it has never bothered me. I'll look into the module deal, but (fingers crossed) it has been fine the last 2 nights. Maybe it really was loose bulbs or did I just stumble across the wire the gremlin was on and shake that lil F'er off? I'm bummed about the cash I've laid out - but happy to have this vehicle back in service. I was about ready to mount a lantern to the rear bumper & call it good.

[malihoochie]

Thanks to all for ideas and moral support.

[TonyHuntimer]

Glad to hear the lights are still working.

For future reference these cool fuse/relays have auto reset or push-button reset for finding problems.
http://www.delcity.net/delcity/servl...age=1&tabset=1


Every time I saw the post about the electrical Gremlin I had visions of an AMC Gremlin Hybrid...

Tony Huntimer