The Stovebolt Site Forums The Shop Area The Electrical Bay Help! Uncooperative Tail Light

I have two tail lights. My truck is not equipped with turn signals. The left and right are wired up in parallel to each other. I was having problems with the left not responding as it should, so I replaced the pig-tail/boot subassembly. Here are the details:

- Left and Right BOTH light up as parking lights.
- When brake is applied, only the right gets brighter. Left light turns OFF completely.
- I swapped bulbs and saw no change.
- I swapped wires on the left and the reaction didn't change, only which filament that was lit did. (I hope I remembered that correctly.)
- The license plate lamp was removed from the circuit during trouble shooting.

I think I proved it isn't grounding because it works as a parking lamp. I think I proved it isn't the bulb because it worked correctly when swapped. There are only two stupid wires here, and I tried both possibilities so I'm having a hard time thinking it is the wiring. I got a new pigtail and saw no improvement over the last pigtail. The only thing I HAVEN'T changed out is the socket/housing, but I can't believe this could be it.

I'm at wits end. Any ideas?

Thanks for any help.

Bill :confused:

parklamp working doesn't mean good ground, it can get a ground via the other light if that has a good ground, but ground has to be good on each light for brake lights to work right - disconnect the wires from right light and see if the left acts the same - check for ground with an ohm meter from the actual socket to the frame

Bill

TxLaTx,

As red58 mentions, it's an easy task to attach a jumper wire to the frame with vise-grips and touch the other end to the brass lampholder. This looks like the only part of the problem that hasn't been investigated.

Stuart

Thanks, gentlemen. Always a comfort seeing input from you both. I'll go give it a shot and see what results and report back. Thanks for the advice!

Bill

Using your advice, I grounded the little tang where the lens screws attach to the lamp housing. I was able to prove the root cause of my problem was (just as you suggested) a poor ground. The bad ground was a result of loose lamp mounting bolts that attach to the bracket. I tightened them up really good and the problem is solved! I'm back to having brake and driving lights.

Much obliged.

Bill

Side note: This was a big weekend for me. I drove my bolt roughly 80 miles on Friday, the most I've driven it in one sitting. I think I was paid a big compliment at the body shop where I'm getting bumper work done. A couple guys came out to do a lookover, and one guy said, "Yep, it even smells like an old truck." ...at least I THINK it was a compliment.

It was. Congratulations!