Reading lights staying on if interior lighting set to turn on when doors opened

[BobHUK]

Hello,

I've got a rather odd problem with the internal lights on my S210, 2002, E220 diesel estate. If I set the interior lights to come on when the doors are opened, and turn off when they're closed, all works well for the front seats, but the rear main light and reading lights over the rear seats stay on all the time. This has led to the battery being flattened when I left the car for a couple of days.

The weird thing is that if I turn off the rear internal lights then they go out, but as soon as I open a door they come back on again, and will stay on if the door is then shut. Meanwhile, the front interior lights go out as they should. The only thing I can think of doing is removing the bulbs altogether, so that only the front lights will come on when the door is opened. The trouble is that this is a workaround, not a proper cure for the problem, and there are times when I could do with having the rear internal lights working, such as when I'm unloading the back of the car.

It occurred to me that the rear door switches may not be closing properly, so I've padded out the plastic covers they butt up against in the doors, just in case. However, I haven't yet actually replaced any of them, but I may consider swapping the front and back door switches on each side to see if it could be the switches that are failing to close properly.

Anyone else had this problem?

 

[Neiltodd]

in mine there are switches in the roof which if accidentally pressed this happens until repressed, nearly had a flat battery once from the rear light I hadn't noticed being left on overnight.

 

[BobHUK]

Neiltodd,

That's what happened to me this morning. Luckily I have a starter pack, so I was able to get the car going again. Since then I've taken the rear roof light cluster apart and removed all the bulbs. So now the only lights that work are the ones at the front. When I took the cluster apart I found there was a PCB in there. I reckon something's gone wrong with that because if I open a door the lights come on, but if I then close the door, the front lights go out, but the rear ones stay on. However, if I then turn off the rear lights with the overhead switch, they go out. So there's something very odd about the wiring of those lights in that they work correctly when a door is opened, but go wrong when the door is closed, and will only shut off when switched off at the overhead switch.

As I said at the beginning of this post, I've now removed all the bulbs from the rear roof light cluster, so that only the front overhead lights now work. That's OK for me though, because normally I'm the only one in the car, and if I do carry passengers at all then it's usually my wife who's with me, and she sits in the other front seat. The rear seats are rarely used, and are usually set down so that I can use the load space for carrying round lots of tools and spare parts for one of my hobbies (sailing and aviation!).