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Electric problem

1K views 4 replies 3 participants last post by  hansa320 
#1 ·
My 92 400E has a mystery about it. The sunroof and/or the driver side window seems to have a mind of its own. The sunroof will close all by it self. I ended up pulling the breaker. Then the driver side window would open any time ANY other window switch was pushed. I opened the door up, and the window motor was receiving continuously 12v in the down position. I swapped out the window switch in the center consol, but it did not help.
I pulled yet another breaker, and the band aid appears to hold for now.
ANY thought are greatly appreciated. The car has 131K miles.
HELP!

Stein
 
#2 ·
Unlike the "first generation" 124 of 1986-1989? which used a simple arrangement of switches, wiring and electric motors, the next generation 124 used a control module for the windows and sunroof. This complication provided neat features like the ability to close all the windows and the sunroof simultaneously using the key at either front door. (Maybe the trunk lock too.)
This control module has a bunch of relays and it uses the window switches as signals, not actual circuit completers for motor operation.
That's about all I know of the system except that the control modules *do* go bad.
Good luck troubleshooting. You need to find tht module and check all the wires to it to make sure that it isn't getting bad info from a shorted switch wire.
 
#4 ·
Under the rear driver's side seat. Cushion should pull up easily from a metal tab. The big box is the comfort control module. The little box is the vacuum control module for the headrests. The comfort module does go bad sometimes; there appears to be some redundancy in the system to help guard against total failure. I'm not sure how you test the box. I would also suggest a shorting wire somewhere as a possible issue.
 
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