Power window problem in W124 (300D Turbo '92) - Benzworld.org

Guest (MBNZ) · 05-17-2002, 12:01 AM

I have a 300D Turbo -92 (W124) with 4x power windows and power lock. I am experiencing a problem with driver-side power window. The problem is quite similar to sue's experiences in his mbnz.org posting '230TE electric window problem' on 2/13/2001 8:33:21 AM. However, the resolution (relay box) provided to sue's case is not good to my problem - I have checked the relay box and I think the defect is not there. Case 0 - Using power lock: In the first place, using power lock made driver window open. Driver window opened without any delay when turning the key to open or close direction. When keeping the key turned, all other windows started opening after a couple of seconds delay (=as they should). When I started investigating the problem, suddenly I noticed the power lock problem had somehow disappeared. This happened about at the time when I had been investigating a relay box (code 124 820 32 26) under the back seat. Case 1 - Door is open and power is off: When pressing driver window switch, the window goes all the way down. There is a relay box (code 124 820 32 26) under the back seat. The relay for 'driver window down' signal will not be released when I release the switch. The relay will not reset even if the window gets down. Since the 'driver window down' relay will not reset I can not close the window. The relay resets if I turn the power on and off again. This strange behaviour happens even if I press the switch only very shortly and I do not press the switch completely down. All other windows work exactly as they should. Window opening/ closing mechanism works also fine from the power lock. Case 2 - Power is off: When pressing driver window switch, the window goes down all the way. Since I have power on, the 'driver window down' relay in the box under back seat resets as soon as the window reaches its downmost position. Now, I can close the window again. However, the problem in this case is that window can not be opened partially. This strange behaviour happens even if I press the switch only very shortly and I do not press the switch completely down. Notes: I have tried changing driver and passenger-side power window switches. Driver switch works perfect in passenger window. And the problems with driver window can be reproducted with the passenger-side switch. I have opened the door panels. In driver-side, after having pressed the power window switch, there is a continuous signal in the 'open wire' that comes to window motor. I have changed the power window & power seats relay behind fuse box to a new one. Removing this relay resets the window mechanism, but did not fix the problem. I would appreciate any idea for fixing this defect. -Tuomas

Guest (MBNZ) · 05-17-2002, 09:45 AM

It's not the switches. If you had a bad switch, the window would not work at all or intermittantly, or the fuse would blow because the fuse was shorted out. 
 
It's not the motor or the regulator since the window goes up and down. 
 
It's not the wiring since you can get everything to work. 
 
My guess it's either a relay problem or a bad ground somewhere. You will need to check for corrosion, and loose grounds, and chafed wiring harness. You may have to refer to the electrical diagram trouble shooting manual. 
 
Hope this helps, tell us how it turns out.

Guest (MBNZ) · 05-28-2002, 09:14 AM

Chris, thank you for your comments, they put me to rethink the possibility of relay problems! 
 
 
Resolution to the case was quite surprising: 
 
First, I took the relay box (code 124 820 32 26) under the back seat to a electrician. He checked the box thoroughly, but did not find any defect. 
 
Next, even if the box (a.k.a. 'Comfort control' or 'control box for power windows and sun roof') appeared to be ok, I decided to try buying a new one. (By the way, the box had changed part code at some point - the new code is 202 820 09 26.) The box was terribly expensive in Scandinavia, so I ordered one from a dealer in Germany. In Germany the price was half of the price here. The new box fixed all the problems I had with power locks and power windows! 
 
 
-Tuomas