Central locking/sunroof C300CE

[43453]

I have a 1991 C300CE which has suddenly developed a problem.

Having worked properly since I bought the car in April, the sunroof switch inside the car seems to have developed a mind of its own. At the moment, it works on the slide mechanism, but not always on the tilt option.

When I get out and use the key fob to activate remote central locking, the doors lock, but then the sunroof tilts open and I hear the noise of a motor whirring somewhere to the rear of the car. I can get round the problem by closing the sunroof manually and locking the car with the key rather than using remote central locking, but then when I unlock it the alarm is activated.

I have checked the fuses and replaced the batteries in the key fobs, with no success and cannot find any clues in the owner's manual.

I had a car some years ago (not a Mercedes) in which you were able to use central locking, but leave the sunroof open, for example to allow air in for a dog, but can find no reference to anything like this in the owner's manual for my car.

A second problem on which someone may be able to advise me is the fact that the seats do not seem to lock into position when the car is being driven. I note from the owner?s manual that when the doors are closed and the engine is running, the seats should be locked into position. Is there a simple solution to this ? rather than stripping out the seats?

I would be very grateful for any suggestions.

Many thanks

 

[Spike]

Interesting problem with the roof but I'm stucjk for an answer at the moment - I'll think on it a while & maybe something will spring to mind.

As for the mechanism for the seats, they are vacuum operated. under each seat is a little rubber hose. make sure they are connected properly.

If they are and they are not working you may need to take the back of the seat off to see if the pipe has come off internally.

To be honest, i think it unlikely that both seats would develop this problem at the same time (unless cause by vigorous underseat hoovering). Have you checked all your fuses - maybe your seat and locking problems are related as they are both vacuum operated.

 

[43453]

Thanks Spike, I'll check that out and hope it doesn't come to removing the seat backs!

 

[300TE Battle Wagon]

If your car has an after market, or indeed Merc alarm that has a self closure function then this may account for the sunroof if the switch is dodgy. I had a BMW with the same problem and the roof thought it was open when it was'nt, when you closed the car the alarm helpfully closed the roof for you but as the switch/sensor was dodgy the roof actually opened! Like your car using the key got around the problem. As for the seats I dont know unless they are supplied by the same pump as the central locking wich is an easy check under the right rear seat - well it is in an estate and saloon! i have had problems with perished hoses but a bicycle tyre repair kit prevented having to remove the complete length of hose

 

[justin1820]

the seats are vacuum opperated from the engine along with other things eg the headlamp level, it only takes vacuum loss on on the system to stop other things from working ok. if you take the pipe off from under the seat and have the engine running you should be able to feel vacuum on the end of the pipe, and as for the sunroof i think that the alarm sounds like the problem and the total closure of the system.

 

[43453]

Central locking/sunroof on C300CE

Thank you for the advice, I think the next stop is the alarm specialist.