In a previous post on Chasing Gremlins I documented problems with the courtesy lights coming on when they weren’t supposed to. I fixed this problem. Several times. In September it came back. The courtesy lights are coming on and staying on.
Thoroughly frustrated I parked the car, disconnected the battery, threw the car cover over it, and moved on to other projects.
Last week I decided it was time to tackle this problem again. Pull the car cover off and reconnect the battery. Yup, the courtesy lights are on.
The first step was to spend a couple of hours spelunking through the wiring diagrams in the Factory Service Manual. With a somewhat better understanding of how things are connected dive into the car.
Starting with a brute force approach I pulled the fuse for the dome light. Which also powered the tail lights, rear turn signals, and brake lights. The tail lights went out and the courtesy lights remained on. Not what I expected.
Pulling the main fuses that power all of the interior circuits turned off the courtesy lights – but nothing else did. After several hours of electrical troubleshooting – also known as electrical frustration – I called it quits for the day before something bad happened.
Going back the next day I started with again studying the wiring diagrams. OK, let’s take a close look at this: the dome light, front door courtesy lights, and map light all come on when you open the doors, so they are all on the same circuit. So why can’t I find the dome light on the wiring diagram?
Background info: The dome light isn’t installed. The dome light housing, without a dome light lens, was in the trunk when I bought the car. And you can’t find the lens anywhere. I never installed the dome light – it is sitting in a box of parts somewhere. So I haven’t actually seen the dome light work.
Just a minute – there is the dome light, buried in tiny print in the corner of the wiring diagram. It isn’t part of the same circuit as the courtesy lights and map light. Huh. Well, that changes things. No wonder pulling the fuse had no effect! Bit in the butt by my assumptions yet again.
Pull the trim panel in the passenger footwell and study the wiring there. Everything looks OK…
Push in the door switch – and the lights go out. Odd… Close the door. And the lights get dimmer but stay on. Interesting! Play with the door. If you push on the door hard the lights go out. Open the door a fraction of an inch and the lights come back on. This is looking like the switch is right on the edge of on/off when the door is closed.
Get a thin piece of wood and tape it to the door where the switch touches as a shim. And now the courtesy light go on and off like they are supposed to.
This could explain all of the symptoms I’ve been seeing and fix the problem. But I’ve been here before. I’ll make a permanent shim since this is clearly a contributing factor. Hopefully this is the final fix – but I’m going to keep my eye on it.
The next project is replacing the door card on the front door. This will give me access to the inside of the door so I will double check all of the wiring while the door card is off.