ok hey guys i have read some post but my deal is different i have a 87 fc and my tail lights dont turn on when i turn my head lights neither does my instrument panel on my brake lights work but not my tail light i dont see how the switch could be broke if when i turn on my headlights then work and i have a alarm and when i turn it off my lights light up all around so it cant be a short so only thing im really going with is a switch but its funny because this happened before and when i took it to the audio shop when i got my car back they were working so idk

 

See the FAQ for instructions on how to repair/replace the headlight switch, and check the harness leading to it as well.

 

Punctuation is your friend!!!

I agree with Aaron. Check the headlight switch. See if the plug in the back is burned or blackened, as well as the harness.