QuestionQUESTION: Out of the blue, the tailgate window on our 2002 325xi has begun opening at will. Sometimes in the middle of the night with the car off. This turns on the interior lights and causes starting/battery problems. We've had the car for a year. This is new. We only have one key and the remote function is not reliable so we manually lock and unlock the car.
ANSWER: obviously a wiring problem, likely a short, or a bad relay. Need to start tracing the wires.
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QUESTION: Any thoughts on where to start? At the lock mechanism? At some control relay or control mechanism? Any tips on locating shorts? Any areas more typical to cause shorts (ie prone to chafing wire)?
AnswerI'm not familiar with that model, so much of this is just good procedures
A good way to chase shorts is to check from the far end (like the fuse), then keep eliminating half of the circuit at a time until you get to the problem. Your problem, of course, is that it is intermittent. It might not be bad when you're measuring it, so you wouldn't see it.
If on this model you can open/close the window from the tailgate key, I would check out the wiring around that. If there is another switch for this window, check the operation of that switch too. Should it be the same as another switch (like the rear door windows), swap switches and see if the problem follows it.
Another point to look at: I'm assuming any interior switches don't operate when the ignition is off. If that's the case, it points to the tailgate switch again.
I'd remove the tailgate interior panels and look at the area around that key switch.
Another alternative: Do you use the tailgate window? If not, it would be very easy to disconnect it, and not worry anymore.
Last thought: Does the remote have a means of opening/closing that window? If your remote function wasn't reliable, the module for the remote maybe telling it to operate.
Electricals like this just take a lot of sound, reasoned debugging. Good luck!
