Tail Light Outage

My car is a 1992 Buick Century with a 3.3 liter V6. My tail lights, parking lights and dashboard lights are out. I checked the fuse in the fuse panel and it’s good. The light switch is good, I confirmed it by inserting a voltmeter in the empty fuse socket and turning the switch on and off. The wiring diagrams in my Chiltons manual are no help. The diagrams don’t include the lighting circuits. Is there another hidden fuse someplace? Could it be a bad relay? If so, can anyone tell me where the lamp relays are located? Any ideas will be appreciated.

I am a little confused here. If there is fuse that controls the parking lights, tail lights, and dash lights, I think it would be between the battery and the switch. I don’t think this circuit involves relays. Describe how you used your voltmeter to test the switch at the fuse panel.

Hello Triedaq, I removed the fuse labeled “tail lights” from the fuse panel inside the glove box. I inserted a voltmeter between the two fuse contact points. I turned the light switch on and off repeatedly and saw the meter needle move repeatedly. That’s how I know the switch is good.

The tail light fuse supplies power to the headlight switch. You must be seeing power back feeding from the switch with the fuse removed. This is not the way to test this circuit.

Measure the voltage on both pins of the fuse with the fuse installed (a test light is easier). There are access slots on the top of the fuse. This quickly confirms there is power and the fuse is good.

Next remove the headlight switch and check for power input on the orange wire and power output on the brown wire with the switch on.

Good comments above. One more thing that might be of help if you remain stuck is a trip to your local public library for the actual schematics for your car. Chiltons manuals sometimes has the schematics you need and sometimes they don’t. But schematics for your car, make, year, and model are available. And the librarly will likely have the schematics there, either in the MOTOR or the other (forget the name) compendiums public libraries usually have in their auto repair section. Even better, ask the librarian if they have the All-Data computer database service. If so, that’ll likely serve up the schematics straight away without having to wade through the MOTOR manuals. I think this won’t prove too difficult to solve. Best of luck.