The Stovebolt Site Forums The Shop Area The Electrical Bay Dim tailights

I got stopped by the police last night because my taillights were so dim they didn't look like they were working. I had installed a new wiring harness last summer and added a second taillight and turnsignals, but I kept it 6 volt. Since everything is basically new, and worked fine last year, I'm thinking a poor grounding problem. I removed the taillight lens to troubleshoot, and found that the bulbs were coated on the inside with something that makes them look like a mirror. It's no wonder they aren't putting out any light. Anyone have a clue what caused this?

Sounds like vaporized deposits from the filaments. Must be pretty old bulbs. I'd think it's pretty rare for two bulbs on the same truck to survive long enough to develop the deposits. Usually the filaments break first.

Get some new bulbs and make sure you have clean sockets and good grounds. If the inside of the taillight housing is not clean and bright, paint inside with chrome or aluminum paint.

Some of the old glass lenses get pretty dark as they age.

Joe

I just discovered my truck had an 8 volt battery in it. I didn't know there was such a thing. Could this have had anything to do with my taillight bulbs turning dark?

Yes, definitely! Your voltage regulator is probably adjusted to 9.5 volts, which makes the lights burn too bright, and coats the glass inside the bulb with tungsten vaporized off the filaments. Get that regulator adjusted, and replace all the bulbs, headlights included. Check the grounds too!
Jerry