My Overhead Interior Lights were staying illuminated very dim when the doors were shut on My 1994 STS. When I open the door they would cut off. I had a new headliner put in one day prior to this issue. I returned the car to the installer and he returned the car to me and stated the lights were turned on by pressing them individually, and he had turned them off. When I left work and was in the car I noticed the lights do not work at all now. I replaced the courtesy illumination relay and the overhead interior lights still do not work only the floorboard interior lights work, any suggestions what I need to look for to resolve this issue. Please reply. The installer of the headliner stated the STS was a nightmare when it come to replacing the headliner, what could they have done to cause this issue?

 

Interior lights are tough, they are generally a large circuit running all over the car. They usually work backwards, they are fed b+ power at all times and grounded to make them work. Somewhere you have a high resistance ground, that's why the lights are on dim. Putting a screw partialy through the wire or pulling the wire against a sharp edge and partially grounding is probably what is wrong. Have the problem present and watch the lights as you move the wiring. If you move the bad wire you will see a change in the light, gets brighter or dimmer depending if you made the problem better or worse. I hope this helps you out.

 

Found the culprit. I had no idea that there are seperate fuses for the floor interior lights and the overhead lights. All I had to do was read the owner manual and pay attention to detailed information. Thanks for your input.