Rear door light in when door is closed.

[Caddynewbie36]

Hi when I start my caddy 2011 van the lights are all out after unlocking the van. Then I drive down the road a bit a the rear door warning light comes on the dashboard and the rear interior light comes on. Even though the rear door is closed the light will not go out. You stop on the side of the road to check all the door lock them all unlock them all, start up the van again the lights not on. Drive down the road and both the rear interior light comes on and the warning light on the dash even though all the doors are closed. What can this be is there anything I can check or do to sort out the problem please ??

[Doc]

On your generation of caddy, this is typically water ingress in the rear door bottom lock.
Most often this is down to a cracked high level brake light.

Check your high level brake light is ok, if not then replace it. Then, get to your bottom lock on the bigger door and dry it out.
Even if the high level brake light is ok, you might have another source of moisture such as condensation or a leak on the rear screen wash.

[Caddynewbie36]

Ok thanks I will take off the panel a check thanks I’ve recently removed the rear wiper as it was broken so could be the rear washer pipe leaking. Thanks for the info will give it a go fingers crossed it solves the issue.

[Caddynewbie36]

I’ve removed the panel a there is no water anywhere to be seen I’ve sprayed some silicone lubricant an wd40 in there a left the ply panel off to see if that helps. But the light still keeps coming on not straight away when the engine starts a little while after. I then have to turn off both the rear a front interior light as they will not go out at it thinks the rear doors are open. I checked for any warning codes a found nothing. I’m really wondering what it could be was working fine yesterday a now it will not go out.

[Doc]

Moisture inside the rear door lock is not going to be visible without taking the lock apart.
What condition is your high level brake light in?

Is your side door closed and latched fully?

[Caddynewbie36]

Hi I recently replaced the rear high break light as the old one was cracked that was a month ago. It had a decent rubber seal around it. I’m thinking maybe I should take it off an apply a bit of clear silicone to the back of the light before reinstalling it ??

[Caddynewbie36]

Oh and I forgot the side door is fully closed an all ok as far as I can see thanks.

[Caddynewbie36]

Checked the top light an it’s intact a not got any water in it. It’s driving me crazy as there isn’t any water in any of the parts mentioned as far as I can see I’ve had a heat gun on low trying to dry everything out. But no joy the light still comes on an it’s the rear door as a different warning light come on when the side door is open. I’ve got the top light apart a gently warmed up the light connection just incase it’s damp an no joy. I warmed up the whole back door before the ply panel the same yesterday an it still keeps coming on. What else could it be an if it’s a micro switch where is that an is it costly to replace or have replaced please ?? Any help and advice is gratefully received.

[Doc]

Is the door latching shut fully, the latch should click twice as you shut it. Maybe try latching it with a screwdriver or similar and see if the light goes out.

If you have a highline instrument cluster, you are correct the rear and side doors are shown as different doors and not just a generic symbol.

I've never had to replace a switch, if I remember correctly it's built into the bottom latch. I recall you can remove the plastic cover to get to it better with a heat gun or hair dryer.

[Teflonaid]

Having the same problem with the snow condesating in, if you lock your door whilst its open do you see any water on the latch ?

Thanks to the above thread im going to look at my brake light for any cracks.

[Caddynewbie36]

The problem with mine was water in the bottom part of the locking mechanism or sensor. I got a hairdryer and a paint stripper heat gun to gentle warm it up a dry it out. All works ok now an as a precaution I covered the sensor a lock in the bottom of the left hand rear door with silicone grease so water or condensation can not get back in. Thanks for all the ideas and help.