One day, the driver’s side door lights just stopped working. I first noticed it when I pulled into the garage and the door lights were off, but the next time I got in the car they were on. A week later I noticed they were off and weren’t coming back on on their own.

When the door was open, the door lights were off and so were the dome lights (unless I opened the passenger door, which did turn on the dome lights, and of course its own door lights).

I first tested the wires going to the switch, which are a black wire to ground and a purple/blue wire to the door harness. The black wire did indeed have ground, but the purple/blue wire was disconnected, showing neither ground nor 12v. Something was wrong with the wiring.

The wiring harness for the driver’s door runs from the switch at the front of the door jamb, around the footwell, down the center console and into the relay compartment, then across the back wall of the parcel shelf, up to the roof and down the door. That’s a long run of wire to look for a break in.

I asked for advice on DMCTalk.org and was pointed to the diode bundle on the right side of the footwell near the center console. These make sure that the door switch only turns on the dome lights and not the other door’s lights. This also means the problem isn’t with the diodes, since the doors aren’t powered from them.

Still, I tested the diodes, and they seemed fine. I removed the parcel shelf back wall to get to the door connector, but it’s tucked so far behind the engine cover release that I didn’t want to have to deal with plugging it back in, so I just left it. I instead found the purple wire (which provides 12v to the doors) in the relay compartment and confirmed it had 12v. I then tested the purple/blue wire and found no connection again. These tests were done with a PowerProbe, which has a sharp point that you can use to pierce the insulation to reach the wire without leaving the wire overly exposed when you’re done.

The next place to look was the door harness. I lowered the window and popped off the upper trim’s fir trees with a long pry bay. The most forward branch of the harness goes down to the lights. I cut the loom tape and tested the wires with the power probe, found no connection on the purple/blue wire, and then thought to apply ground to the wire. The lights went on. That showed that I didn’t have to take the door apart any further.

I went back to the relay compartment to do the same test, but the trick is figuring out how to see the door while poking at it with a PowerProbe. I finally propped the door partly closed and pulled out the rear light so I could see it more clearly from behind the passenger seat. Once the purple/blue wire was grounded, the door lights came on again. This showed that I didn’t have to take the upper door trim off, either.

Propping the door closed enough so that I could see the dangling rear door light while powering the circuit from the relay compartment.

I went back to the diode bundle in the footwell and tried applying ground there, and nothing. I the wires from red diodes as well, and then noticed that one of the two purple/blue wires in the connector was broken. I didn’t notice before, I think because the broken end was still in the loom tape.

I cut the tape away and found the other end of the wire. I slipped on some heat shrink tubing, stripped both ends, hooked them onto each other, soldered then and shrank the heat shrink over them. Then I got to spend the next 20 minutes putting the door and parcel shelf back together.

But at least the door lights work again.