Help: 2003 BMW 325CI intermittent interior lighting
When the car is locked, and turned off, the interior lights come on intermittently. This morning I walked by the car and it was on (I don't know for how long), and twenty minutes later when I came back home it was off. Later in the evening it was on, and it went off by itself. I never see when it comes on exactly, or when it exactly goes off. These aren't the reading lights; they are the interior lights triggered by the door. I fiddled with the 'light' button at the front of the vehicle, but I doubt that this is the issue. I just bought this car yesterday, and I already have a feeling this issue is going to cost $1000 to diagnose and repair.
One possibility is that the contact switch in the door latch has become worn out. In the door frame, the part that sticks out to hold the door has a micro switch in it. When the door is closed it sends a signal to the computer saying so. When the switch doesnt work it can't tell if the door is open or closed, thus triggering the interior lights.
Sounds good. Let us know what happens. Check your weather stripping too just in case. A few people said their weather stripping around the door was abnormally thick and was causing the door to not seat right and not make contact with te latch striker properly.
I'll check the weatherstripping, but I can only compare both sides to each other. The interior fabric trim running around the door opening is missing on the driver's side, probably due to old adhesive wearout. Maybe this is a possible cause?
Aside note: There is a small, red plastic lens/light below the rearview mirror. Is this an alarm feature, manufacturer or aftermarket? There appears to be a very small, square sensor/chip exposed in the center of the rearview mirror. Is this related? I don't have a remote for the vehicle, so I have no method of testing.
That red light under the mirror is in fact for the alarm. They were included on all models. To find out if you have an alarm look behind the drivers headlight under the stock airbox and you will see (or not see) the alarm siren.
I had the door open today, and the interior lights did not illuminate (none of the three) so I do believe it's one of the door mechanisms. Yesterday, the lights came on just fine. I checked the weatherstripping and both sides appear to be in good condition with no apparent bulging.
Does your door sound like it latches properly when you close it? Check the latch mechanism to make sure it functions and you can add a lubricant such as white lithium grease or graphite to help keep it working smooth.
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