Desperate for elctric window fix

[Timbo]

I have a 98 230k c class, the problem is that the front windows keep failing to operate. If I disconnect the battery for a few minutes they work for while, maybe a week or just a few hours. This morning I went through the process again, but by this afternoon they both stopped working. Can anyone help, they are driving me mad. I need to fix or she'll have to go.

 

[Wisher]

i know this may sound silly.. but sometimes it can be the switches... not making a connection....
or the fuse may be on it's way out...replace the fuse anyway..

 

[Timbo]

wisher, unlikely I would have thought, why would the windows work imediatly after disconnecting the battery? must be a computer tupe thing don't you think. Have checked switches any how.

 

[Wisher]

I don't know anything about the computer workings in a car...

it just seams strange that it's two windows that are playing up.. thats what made me think it could be a fuse...

 

[trueblue]

wisher, unlikely I would have thought, why would the windows work imediatly after disconnecting the battery? must be a computer tupe thing don't you think. Have checked switches any how.

When you state you have checked the switches... Does this mean you have opened up the switches and cleaned the contacts ?

Have experienced this problem in ever increasing frequency over the years on my recently departed 230TE (have replaced it with an E200
Elegance Estate, 1997 - bought on Ebay - think this was my biggest
mistake ever, the amount of problems seem endless, all due to lack of maintenance ! )

Back to switches, dismantling is straightforward, do not lose ballbearing
from inside - look for carbon deposits and pitting on several of the large silver contacts, scrape clean gently and use finest grade of emery cloth,
600 grit or so, to reshape and repolish silver contact points on both upper and lower pairs.

My drivers side used to stop most frequently, followed by passenger side,
rear windows never had any problem due to minimal use.

trueblue

 

[Mr Fridge]

If your car has rear electric windows can you swop the switches around to try, even if they are the wrong shape the wiring connectors will be identical.

 

[Timbo]

Thanks guys for your replies, I think it is definately not the switches, I have tested the circuit with a multimeter and there is no juice when I get the problem. The strange thing is that they will work after the battery is disconnected, I would have thought that if the switch was duff this wouldn't happen, plus it could be nsf or osf or both that fail at any time, the chances of two switches going together I would think are rather remote! The system on the c class I have now is not like the 230te and 190e I had, there seems to be only one power lead to each window and I'm guessing that each motor has its own relay, the other wire are definately too thin to carry much current other than to operate a relay.
I notice also when this happens that the coresponding electric mirror also fails to operate. The car has full window and sunroof closure which is operated by the remote key, this also plays up, don't know if they are connected. I just feel that disconnecting the battery might be reseting some kind of memory device?

Thanks again

 

[Mr Fridge]

Sticky relay contacts, when you disconnect the battery the relay contacts relax, when reinstating power the windows probably operate a couple of times, I would say either a relay or master relay for all the windows or even a bad earth which is creating an holding circuit thus preventing the window motor to work. How practical is it to hot wire the window motor direct from the battery to prove that the motor is working and not cutting out on some kind of internal thermistor or over current cut out.

 

[Timbo]

Interesting sugestion Mr.fridge, but would the same relay control the electric mirrors as well? do you know where the master relay is? and what are the chances of 2 switches/relays going at the same time? I reset it again this morning and so far today all is well, until the next time. Do you think it would show up on the fault diagnosis equipment at the dealership?

thanks again

 

[Mr Fridge]

Not if it was an earth fault as it would be intermittent.

 

[jaymanek]

You have to teach your windows if they lose their memory... I think after connection to battery its a sequence of dropping and raising them... The procedure should be outlined in your owners manual...

 

[Timbo]

Popped into the dealership yesterday, a very helpfull chap said they had had a similar problem on another c class, it turned out to be the switch block around the gear lever. it carries all four switches, replacement cost £147 plus vat. So i think I might investigat this further.
No problems with rear windows, as someone suggested less use, but I don't think I can swop switches as they are all fixed together. Aparantly the fault causes some duff signals to be sent to the computer, disconnecting the battery resets this untill the next time. What do you think? sound credible?

Timbo