My guess here would be to try wiggling your door switches a little or even just push and let them go a few times with your hand. Otherwise, if your car has one, turn the rear light switch in the middle of the dash board on and off a few times. My final thing to check is make sure that none of your power seat switches are stuck. I had that issue when the passenger power seat switch was somehow stuck in the middle and it caused the car not to start. The moment I got it unstuck, saw the interior lights go on and the car was able to start.

On my 1987 W124 the trunk light was staying lit and drawing the battery down. It is easy to remove bulb and do your checks again.

Aha! That's like wondering if the fridge light goes off when you shut the door. Everybody assumes it does, but do you every really know? So, did you actually have a helper shut you in the trunk to see... and trust them enough to open it again?

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Cheers!
Scott McPhee

1987 300D

Actually if dark outside on my car you can see a wee bit of light by the 3rd brake light. I had my 3rd brake light off recently and must not have slid it back together properly. Good question tho. !