Join Date: Dec 2001
Location: Belleville, Illinois
Thanked 22 Times in 17 Posts
Re: CJ- Taillight problem? Need help ASAP
If the brake lights are full brightness, it's not a ground problem. The brake light filiment and the tail light filiment are in tthe same bulb, and use the same ground. If the front parking lights don't work either, I'd suspect the ignition switch.
The parking/tail lights are fed with a white 16 gauge wire that runs from the switch to the firewall connector, where the front lights get their power. From there, to the rear, it runs through a harness connector, to the left tail light, the left side marker, the right tail light and the right side marker, in that order. According to the '78 FSM.
The power for all the lights goes from the battery directly to the switch. There is no fuse in the line; just a fusible link in the engine compartment. The switch has a thermal circuit breaker that takes care of all of the light circuits.