My car was rear ended several months ago. Got the car back from body shop but the tail lighting isn't working right. 1989 Firebird with base model Firebird tail lights. Below is a description of symptoms. Any ideas what could be the cause(s)?

1. Bulb on far left in the photo (combination parking/brake light) doesn't work properly. The parking light circuit only turns on intermittently and the brake light circuit seems to work fine. Both circuits use a common ground so I suspect the ground is fine. And I can't blame the problem on the parking light power wire either because the other parking light works fine (both lights are powered by the same wires). I have cleaned the contacts and barrel of the bulb. I think I will change the bulb tomorrow but I have a hard time believing a bulb could work intermittently?

2. Turn signal (right and left) runs very slow when parking lights are on, and speeds up when parking lights are off.

3. What is the bulb on far right in the photo? It has never turned on for any reason yet. I don't even know what purpose it serves.

 

Answer to #3 is backup light. Duh... I feel like a bit of a dumb nut.

Still wondering about #1 and #2.

 

Answer to #1 is apparently a bulb can be intermittent. New bulb and lights are working again. Thanks goodness I didn't have to repair wiring! I went ahead and replaced all the bulbs on both sides of car so I don't have to go in there again. I don't recall ever replacing a bulb in the last 25 years so they are all probably the factory originals.

Interesting thing is the flasher works better with car running (higher voltage). I went ahead and bought a new flasher.