Temperamental window switches
 

The electric windows on my 75 stopped working from the driver's door switch pack last autumn. The three passenger windows would still work from their respective door switches, but the driver's window wouldn't open at all. There was still power going to the switch pack as the mirror adjustment worked, and the light still came on in the rear window lock button when pressed (although it didn't actually lock the rear windows).


I took the switch pack out and dismantled it for cleaning as I'd been told they can suffer from manky contacts, but all the contacts were absolutely spotless. I tried a different switch pack, as well as a different BCU, but this made no difference.


Eventually the windows started working properly again so I didn't bother investigating further. However since I disconnected the battery to replace the ECU they've started playing up again - now they'll work occasionally but more often than not the driver's door switches won't do anything.


Does anyone have any ideas what could be causing it or will I need to take the car for a T4 session? My aircon doesn't work and with warmer weather supposedly coming I could do with a full complement of opening windows.

You say the contacts were spotless but did you clean them anyway. I had bother with the door mirror movement on my old 1.8T, the contacts didn't look dirty but everything worked perfectly after cleaning. Looking spotless and being spotless are two different things. Best thing I ever found for cleaning them is a fibreglass pencil.

As Steve suggests, we cannot see what causes the loss of electrical contact, so go through the motions anyway.
I used a pencil eraser.

Also, opening the windows is not a fix for failed aircon - get the aircon fixed too! :}

I didn't use a fibreglass pencil (thanks for the tip though, I will invest in one) but I did give everything a good soaking in contact cleaner when I had it apart. I really don't think the contacts are the cause of the current issue though - at the moment either all of the switches work or none of them do, if it was faulty contacts I'd expect just one or two to play up at a time.

I attempted to fit a new aircon belt last year and failed miserably (bought what everyone says is the correct belt but it was nowhere near long enough) and it's a job I'm in no hurry to attempt again...

Hello Dave,

First of all thank you for your clear and comprehensive description of the fault in post no. 1.

I've checked the MGR manual and whereas the individual passenger door switches are hard wired to the BCU, all the driver's door switches communicate via a unidirectional dedicated data bus. This would appear to confirm that your fault most likely lies with the switch module or the wiring to the BCU.

Since all windows and the rear locking facility intermittently fail to operate, I would turn my attention to the contacts in the 6 pin connector (C0081) mounted to the rear of the module. Try switch cleaner and/or gently closing the female contacts slightly using a very fine tool.

1 = data stream to BCU
2 = switch illumination PWM signal
3 = 12v auxiliary supply from fuse 11
4 = Earth
5 = not used
6 = 12v battery

I hope that this helps! :}

Simon

Check the multiplug that connects to the drivers door, unplug it and look for corrosion on the pins had one before with corroded pins just gave them a clean and that sorted it

Thanks for this thread everyone. One of my rear passenger windows failed to close a few days ago. Didn't know what to do, so I switched off ignition completely, then turned key to first position and tried again. Worked that time!
I like Steve's fibreglass pencil - might buy one.

Beware. Fibreglass pencils are VERY abrasive. The gold plated contact surfaces are best cleaned with a pencil erazer, soft variety.