Courtesy lights on pass. side doors not working (G50) SOLVED

[db_autotek]

I have this odd problem, the door courtesy lights (puddle lights) do not function on the passenger side. Everything else on the doors works fine, evrything. Absolutely no other lamps are not functional, this may sound surprising I know, but ive spent 6months restoring the car.

Anyone else have this problem before? I'd like some ideas before I tear into the door.

I did try replacement bulbs of course, no luck. I got out my VOM and strangely I have between 1 and 2 volts at the lights. This I thought odd since I expected zero volts.

So far, I have studied the FSM (and studied the rear drivers door since I had it apart to replace the window regulator motor assembly) and come up with some thoughts. It could be wiring being pinched or shorted in the harness somewhere... But both doors? And only the passenger side? It could be the control box in the door panel, but everything else works. And again, the chances of two boxes going out on the same side, while all else works. It's not the door open switches, those all work. I don't seem to have any fuses out.

I may have to rewire both courtesy lights completely. I considered rewiring them back to the passenger side footwell lamp. I'm not concerned with amps since I'm using leds.

[Q451990]

There are a bunch of fun diagnostics in the FSM that show how to run various tests on the LAN system. If you don't have a copy you can download it at www.nicoclub.com/FSM/

From looking at it, I agree that your problem has to be somewhere upstream from the individual LCU units though... It would be strange for both of them to fail on the same side of the car. They do have some wiring in common though - and there's a flow chart starting on EL-201 that should make it easier to check everything. There are also self diagnostics you can run without Consult in that section of the FSM that might point you in the right direction.

Good luck!

Heath

[db_autotek]

Got it sorted out, here's my actions in case someone else runs acrross this problem some day. First, the easy one, the rear door. After removing the door panel, I found a loose connection at the door (LAN) control box and a loose connection at the plug to the door lamp housing socket. Quick fix and now that light works, still no action in the front door courtesy light.

So I studied the FSM for many hours, with the front door apart. Here's the important knowledge: the + wire ito the courtesy lamp is purple with a red stripe, as noted in the FSM and noted in person. This wire is always hot, I found out with my multimeter. This makes sense of course. So I have +12 at the hot wire, so now I know that wire and anything before it is good.

Testing the black ground wire for the lamp, I had no continuity between it and ground with the doors open. I tried it with the door(s) open, and while manually operating the door switch, no effect and no change. So now I know that the ground wire from the lamp to the inside of the car is damaged.

It could not be have been shorted, otherwise the other lamps would either fail to work or be on constantly. It must have been pinched off somewhere.

So now I was faced with a choice, do I continue tearing the car up and pulling out wiring harnesses until I found the break? Or, do I run a new negative wire from the footwell lamp? I went with option B, and since I had the door apart already, it was quite easy to run a wire through the harness sheathing so it doesn't look ghetto rigged. I ran it down by the ac motor to the plug of the footwell lamp and spliced it in with a butt connector. In the door, it was easy to follow the harness and make use of existing points to keep the wire tucked securely.

So there it is... The source and resolution of months of mystery haha.

[Q451990]

Good work!

Heath