The Stupid Electronics Questions Thread

[T-Yaz]

Hoping someone can point me in the right direction with my electrical problems.

When I first bought my truck, I would blow my parking light fuse once I hit about 60mph, black out everything but headlights, but would still have turn signals, brake lights, backup lights etc. I work midnights so my drive to work is solely in the nighttime so you need lights. Got tired of constantly getting pulled over so my fix for the time being was keep it under 55 mph as I can’t afford much as I live paycheck to paycheck.

Couple months down the road it got to where the whole rear half of my truck lights would randomly cut in and out. You could bang on the bed and they’d come back on. Now they’re to the point where they won’t work at all with the parking lights on so I have to keep the fuse out to keep taillights.

- Brake lights come on as parking lights (both middle and top lights come on dim)
- Backup lights only work when not on brakes
- Both blinkers flash dimly in the rear
- Right blinker hyper flashes only when on the brakes, then will flash full power on opposite side only in rear, left the same, minus the hyper flash
- interior lights/cargo lights as well as whole parking light system will dimly flash with hazards when hazards are on

I’ve looked at many forums and asked around but I cannot find anyone with the same or similar issues. A few internet write ups are leaning at the possiblity of a bad turn signal switch or a short to ground going to the back. Any insight would be much helpful as I’m tired of getting pulled over and it’s becoming a serious hazard as I believe I’m to blame for a three car pile-up behind me a couple days ago leaving work.

1994 Chevrolet C1500 SCSB 4.3L 4L60E

 

[df2x4]

Have you crawled under the back of the bed and looked for any trailer wiring that the previous owner may have installed badly? That seems to be the number one cause for issues like this. There's a junction in the wiring back there by the bumper that you can plug a T into to run a trailer harness.

 

[T-Yaz]

Have you crawled under the back of the bed and looked for any trailer wiring that the previous owner may have installed badly? That seems to be the number one cause for issues like this. There's a junction in the wiring back there by the bumper that you can plug a T into to run a trailer harness.

Me and a friend of mine have looked at it, all seems to be okay. Even tried swapping taillight circuit boards with used ones from a same year truck. Ground back there looks perfect.

 

[Blue Turd]

When I bought my truck the brake lights would randomly blow fuses and not work properly. Come to find out the previous owner used to have a cab on the truck, and looks to have just cut the wiring when he removed it. That left just bare brake light wiring whipping around inside the ladder rack hole. It would short out my lights every time it touched the metal of the bed. Took me like weeks to figure it out because I couldn’t see it!

As a lot of us are second, third, forth etc owners of these trucks. There’s always some previous dude before you that didn’t know what he was doing. Especially true with the brake light wiring, as it’s messed with for cabs, trailer wiring, brake controllers, rear aux power, etc. I’d pull a wiring diagram and check all the wires for both continuity and shortage to ground. Also check under the steering column for any evidence of old brake controller. The wiring for the rear lights runs all the way down the drivers side frame rail, so double check that for anything suspicious.

Your issues seem like bad grounds somewhere, so check all those too. Bad grounds always make for weird electrical symptoms and off behavior of things.

Good luck!

 

[T-Yaz]

There’s evidence that my truck has had underbody neon before. Previous, previous owner dumped money into this truck, it has 2/4 drop, has shaved doors and evidence of a previous sound system. From the looks of things, it looks that underbody glow was just tapped into the running lights instead of using a toggle switch. I’m wondering if some bare wire somewhere has been tipping the body when I hit a bump or go 60mph. Not going to be able to do much with it right now, don’t have a way of jacking the truck up and I’m on such limited income at the moment going out and buying one isn’t an option.

 

[Blue Turd]

Yeah that sounds like the type of owner to do improper wiring. Luckily they are usually lazy so when you finally take a good look it should be obvious what they have done.

 

[T-Yaz]

I’ve already had to replace the wire going to the positive terminal of the battery, looked like it was involuntary cut and sloppily reconnected using a way different gauge wire. I would stall the truck turning headlights on and couldn’t figure out why, one day on my way to work my headlights were surging badly, the next morning it didn’t want to start and I feared I needed a new alternator. Found the wire wrapped with half a roll of electrical tape caked in corrosion and had to replace it in pouring rain. Things like to go wrong at the wrong times.

When I get home I’m going to look under my truck and see if I see anything that doesn’t look right. As for getting completely under the truck I’m SOL at the moment.

 

[Blue Turd]

You can always do the ole’ drive up onto a curb trick if you don’t have a jack.

 

[T-Yaz]

That’s not a bad idea actually, if I can’t get under it today, I’ll see what I can do tomorrow. Can’t believe I haven’t thought of doing that.

 

[Eveready]

The fact that it gets weird when you hit 60 MPH may be the big clue here. That almost has to be turbulence under the truck at a certain wind speed blowing some wires around. My guess would be a bare wire from the old neon shorting to ground when the wind blows the wire flat to the frame at 60 MPH. I can't think of anything else that would duplicate that condition. I would definitely get under that jewel with a big roll of electrical tape and insulate anything that looks like it could be moving with rapidly flowing air. Good luck!