Interior light stays on

Someone really over-thought this for you. First, close all the doors but one, and push in that switch to figure out which one is keeping the light on. Once you know that, the repair is really involved. The easy repair is to readjust the switch. I will share the permanent repair later.

The switches have what looks like a plastic nail in the center. In this photo, the blue arrow is pointing to its head. That nail slides in to self-adjust when the door is closed. With repeated slamming, that switch can over-adjust. What you must do is stick a small pick into the slot the red arrow is pointing to, and pull that nail out a little. If you pull it out about 3/8", it will get pushed back in the proper amount when you close the door. That is the normal repair.

To prevent this from happening again, I repaired these at the dealership by pulling the nail all the way out, then sliding three M5 lock washers onto it. If you install the nail that way, the washers will prevent the nail from over-adjusting. To add a professional touch, I painted the washers with black touch-up paint so the silver did not stick out.

I called this the "teardrop" style of switch because of its shape. There is a totally different style that has a round body that can also over-adjust, but resetting that style is done differently. Let me know if you have that and I will describe the procedure.

That plastic nail is about an inch long. All you see of it is the head. Just pull on that head with anything you can hold onto like a pick, a really small screwdriver, a small nail, etc. It will slide out all the way, then you can slide the washers on before stuffing it back in.

What happens is the door normally closes too far, then the rubber weather seal expands and pushes it back out a little. If the door is slammed or if that weatherstrip is deteriorated, the door can close too far before it gets pushed back out. That causes the nail to over-adjust, then the actual switch does not stay pushed in far enough. Often this causes the interior lights to turn on momentarily when you go around a corner and centrifugal force pushes the door out a little more. In your case the switch was not getting pushed in enough to ever turn the light off. Very common problem with a very cheap and permanent fix.