Resolving interior light issues

[AirmanPika]

So ever since I've had the car the rear interior light has never worked. There is zero voltage getting to the lamp. I was able to confirm good ground but I can't trace out where the purple/white wire runs to properly check its integrity.

The front one worked fine till today. I was troubleshooting the rear one again and now its stuck on in both the always on position and when in the door open/closed position (but when I press in the switch it dims and the rear lamp also illuminates slightly). The door switch is fine as it still flips the door warning lamps on and off as needed. I had tapped the power feed from the front light to see if I could feed the rear lamp and verify it worked when power was applied (it does). The issue seems to have started after this.

The interior lighting wiring diagram is useless as they didn't label anything on it. Having read a few threads, I notice that the diodes sometimes cause problems. I found two in the relay/fuse box which are black and I assume to be 1 amp. They both tested fine. There were also 3 up front in the left footwell next to the console. 1 black again, and 1 blue and 1 red. All of these test fine too tho not sure what amp the colored ones are. Behaviors I saw though when disconnecting...red and blue disconnected cause front lamp to dim and rear lamp to partially come on. Black one disconnected didn't seem to change anything.

Not sure any of that helps but I am basically at a loss. Any thoughts?

[WelmoedJ]

So ever since I've had the car the rear interior light has never worked. There is zero voltage getting to the lamp. I was able to confirm good ground but I can't trace out where the purple/white wire runs to properly check its integrity.

The front one worked fine till today. I was troubleshooting the rear one again and now its stuck on in both the always on position and when in the door open/closed position (but when I press in the switch it dims and the rear lamp also illuminates slightly). The door switch is fine as it still flips the door warning lamps on and off as needed. I had tapped the power feed from the front light to see if I could feed the rear lamp and verify it worked when power was applied (it does). The issue seems to have started after this.

The interior lighting wiring diagram is useless as they didn't label anything on it. Having read a few threads, I notice that the diodes sometimes cause problems. I found two in the relay/fuse box which are black and I assume to be 1 amp. They both tested fine. There were also 3 up front in the left footwell next to the console. 1 black again, and 1 blue and 1 red. All of these test fine too tho not sure what amp the colored ones are. Behaviors I saw though when disconnecting...red and blue disconnected cause front lamp to dim and rear lamp to partially come on. Black one disconnected didn't seem to change anything.

Not sure any of that helps but I am basically at a loss. Any thoughts?

All interoir lamps as well as the door lamps are powered directly to the lamps (purple wire).
The other important wire is the purple/white one that runs from the lamps to the delay timer relay (pin 87) and then to the interior lights.
The interior light are grounded through the door switches and through the lamp switch.

In the purple/white wires to the doors are diodes (3 in total).
Banned Bill has uploaded pictures of the locations of the various capacitors and diodes.
Unfortunately I seem to have lost the thread's name.

You may have a bad connection or wrongly connected lamp switch terminals (see John Herveys website for the picture with the proper wire connections or attached his picture).
22280
You also habe a broken wire between delay timer relay and lamp switch (purple/white).
Must be somewhere in the relays/fuses compartment.

How did you check functionality of the diodes?
For a check you need to disconnect at least one of the wires it's connected to.

Good luck in your quest.