Re: Window gremlins.... (archive)

Ok, last week, driver's side window would not go down. I stopped car and shut it off, restarted and bingo it works. Today, passenger side front window would not go down or up. I opened and closed all the other windows and after doing the passenger rear window, then the front window would go up. Is my regulator in the fritz? Is there only one window regulator or one for each window? TIA for any advice.

It sort of helps to mention what model of E39 you have, and model year is also necessary - production date is even better.

Otherwise you get general info as follows.

Your windows are controlled by 3 different computer modules.

The General module (behind the glove box) is the main cabin control unit, and it directly controls the rear windows (the switches are connected to it - not to the window motors).

Each of the front doors has a separate computer module in it that controls all functions in that door (except the lights).

These all communicate by signals on the digital bus (different busses for different car models and years)

Now there is a known issue with cars built before 9/97 that might be causing your problem - which according to your message has only occured on the front doors.

When start the car power is momentarily cut off to many consumers - like the seats, windows, etc.
After starting, they are all reactivated via a digital message - but the bus gets very busy at that time and sometimes the messages get lost.

Restarting can resolve this.

You need to have a GM with software later than Sep 97 (version 2 if I remember), or it is also possible that your current units have incorrect coding and need to be "re-coded" (software re-installed)

If this is happening frequently see you dealer.

Cheers
Jim Cash

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