Taillights not working, diagram needed?

Tiny
JUMUNJI
  • MEMBER
  • 1983 PONTIAC BONNEVILLE
  • 0.5L
  • V8
  • 2WD
  • AUTOMATIC
  • 3,000,002 MILES
Taillights not working.
Wednesday, April 5th, 2023 AT 10:58 PM

1 Reply

Tiny
STEVE W.
  • MECHANIC
  • 12,958 POSTS
The taillights all share a single feed, the brown wire. That wire runs from the light switch back to the lights. I would first check the tail lamp fuse, however if the front marker lamps work then the fuse is okay as it feeds them all. The next step would be to see if the ground at the rear failed. A simple way to do that is to pick any light that is easy to get to and use a pin to pierce the insulation on the black wire. Then take a piece of wire and connect one end to a good ground and then to the pin, do the lights come on? Repair the bad ground wire, it is at the left rear of the trunk bolted through the body. If they don't light up with a jumped ground, it is likely in the harness. Either a bad splice or a bad connector. Attached is the wiring diagram. All marker and running lamps use a brown wire for power.
https://www.2carpros.com/articles/how-to-check-wiring
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Thursday, April 6th, 2023 AT 6:34 AM

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