I've searched but have found that most radio issues are due to terminals or ignition problems. Not the case with my 1990. Everything mechanical to the car runs great. Alternator puts out good volts and battery holds the charge. I have zero other problems except the radio and my interior lights. I've checked all fuses and connections and they all look ok.

Symptoms:

While listening to the radio and you open the door the radio shuts off. Close the door turn the radio back on the presets have all been cleared.

If you turn the dome light on the radio turns off but dome light does not turn on.

If you turn the headlights on the radio turns off.

The door ajar light stays on all the time. Door switches are good and I have cleaned the contacts.

The dome light and underdash curtesy light and key light do not work period.

My Thoughts:
I'm thinking maybe there's a short with the interior lights somewhere? Maybe a wire on the back side of the dome lamp is hitting the roof? But it's not blowing fuses is the strange thing. I don't have a manual for the vehicle. What else runs on the circuit for the radio, interior lights, and headlamps? Thanks in advance for any insight you can provide.

 

Sounds to me like the accessory wire for the radio is connected to the wrong wire behind the dash. Could be hooked to something involving the dash lights which could cause SOME of those problems.

 

The factory radio wasn't removed or messed with, and at one time everything did work. Could the headlight switch and or wiring harness cause issues like this? I don't know if the interior lights are hooked into that harness at all.

 

Sounds like the Room fuse is blown and that the ground for the radio is incorrect.

Where is the radio grounded too? Is it using the stock brackets and they are screwed into the dash?

And you can't just look at a fuse and see if it is blown. You need to check it with a meter or tester.