Mrmerlin

To echo what Hold On said i had an issue with the 82 RR, marker light warning,
finally found it at the RR light connector,
the ground wire was 1 strand and finally broke,
I soldered the wire onto the other one all is good.

Eplebnista

I don't have the ground back there either. I have had this problem 2x. First time it was the white barrel connector under the quarter panel trim and the second time it was a failed bulb control module.

davek9

The License Plate Lights don't go through the Lamp Controller and don't care what you put in them (easily upgraded to LED's .

Check and clean the fuse and that others on the same fuse work, remove the two screws (each) that hold the LP lamp fixtures to the bumper cover and clean it up, check for power and ground at the wires, most are rusted up as they never get serviced until they are out.

Also DO NOT put in bigger lamps than called for in the LP's as they will melt the plastic lenses, I've seen it on more than one car.

Dave