My '80 rear license plate light only turns on when the courtesy dome light goes on; that is, when opening the door or turning the light switch to turn on the interior light on. Should it not come on when the headlights are turned on. This seems very strange to me. Thanks.

 

Absolutely. It should be tied in to the parking light circuit. As a shortcut to get legal, you can use a jumper wire from the rear parking lights to the license plate light, and then track down the real issue when you have some time to play "find the wires" (not my favorite game). Splice into the positive side of the parking light wiring, and jumper that over to the positive side of your license plate light. If you splice into the negative side of the parking light, or go in series, the license plate light won't work when you lose a parking light bulb.

bill.