Left rear tail light assembly '02 Chevy Venture

I’ve had problems with my left rear tail light assembly for a while. I replaced some bulbs that looked like they were out, but it seemed the circuit board (basically 4 sockets that snap into the red/yellow lens on back) had a bad socket. So I ordered a new one at an online car parts store. I put it in, but I noticed the wire assembly didn’t snap in as well as the original. Had to force it in to get a good electrical connection–no snap fit. It worked fine for a few weeks, but then I noticed that when I hit the brakes, both turn signals lit up like the hazard lights, but no flashing. When I turn on the left turn signal, it works fine, but when I hit the brakes, the turn signal starts flashing faster (this is a sign of a burned out bulb in most GM vehicles). Let off the brakes and it flashes it’s normal speed/cycle. I also noticed the traction control warning light came on. When I’d take the light assembly off and push the connection in, everything works fine for a while, but the above problem always comes back.

I returned the above circuit board and bought a genuine GM part from my Chevy dealer (electical plug snapped in like it’s supposed to). Everything worked fine for a day or two, but then the above problem happened again.

I carefully test all the lights once the assembly is reattached to the car and everything works at first, but after driving, it seems to slide back to the same problem. I’m thinking there might be a short somewhere in the wires running to the plug that plugs into the circuit board. When everything is put back up against the car and bolted in, the wire could be touching metal and shorting out or a couple of wires could be touching somewhere. Any idea what my problem might be?

It sounds like the brake light and turn signal lines are getting crossed somehow. Sometimes this happens when the dual filament type bulbs are used. The filaments get crossed inside the bulb. If you use that type of bulb then check them out. It can also happen when the bulbs aren’t turned in the socket correctly. Another possibility is the wires are getting crossed somewhere and when you work on it the trouble clears for a while. If you have a trailer wire harness check that out. You will most likely find the trouble there.

I think I used a new bulb. It happened on a different brand bulb, too if I remember correctly. But I’ll check the bulb to make sure. It’s one of those bulbs that you push in, not screw in.

“Another possibility is the wires are getting crossed somewhere and when you work on it the trouble clears for a while”

Yes, that’s what’s happening. I check things 3 times. I check the bulbs in the circuit board w/it outside the circuit board, then I check the circuit board inside the lens, then I check it when I attach it to the car. It sometimes fails when I get it attached to the car. But when everything works after it’s attached to the car, it will work for a while (say an hour, a day or even a week), but then will fail eventually. Getting to be a headache. Since it happened with two different new circuit boards (the original board definitely had a burned out socket, though), I’m pretty sure the problem is in the wires to the board. I’ll have to look that over closely. That will be a pain if I have to replace that. I don’t have a trailer wire harness on this van.

Sounds like a poor ground problem, where the power goes thru other lamps to get to ground. 12 volts ain’t much. Kinda’ like that old 3 volt flashlight that you have to bang to make work, even though the contacts LOOK clean. If you can find the wiring diagram for the lights, confirm every ground is clean and tight, or even run a jumper to a known good ground to see if it solves the problem. Buying the GM service manual was the best money I ever spent, saving many hours and many shop calls.

Well, I took off the assembly (both sides) and interchanged the circuit boards and they worked well for both sides (interchanged). Then Put the left circuit board on the left wire harness and played around with it. I found out I could make it fail if I wiggled it slightly so that it was pulled out a little, say 1 or 2 millimeters, even though it clicked in place when I pushed it in. So I put everything back in place on both sides and when I put the left side back on the car, I made sure the wire harness was pushed in as firmly as possible and put the left lens back on the car. Tested both sides and they both worked properly. I even pushed on the left lens a bunch, trying to simulate road vibration, etc., and it kept working properly. So I think it’s the circuit board itself. I also messed around with the wires, pinching them together in different places where they might be pinched inside the assembly and I wasn’t able to get it to fail. Problem seems to be in the connection to the circuit board.

I guess if it fails again, I’ll return it to the Chevy dealership as it does have a 1 year, 12,000 mile warranty.