Weird electrical problem
Thread Starter
Newbie
Joined: Jul 2024
Posts: 4
Likes: 1
From: Spokane WA
2003 C230K coupe
Weird electrical problem
I've tried searching but couldn't find anything with the same issue. I'm hoping someone here can help or maybe point me in the right direction. Here's the issue:
I have a 2003 C230 coupe. The driver door window switch will roll down the driver window but not the passenger window. I know the passenger window motor works because I can roll it down using the key fob. The passenger side window switch operates the driver side window (WTF!)... Also, if I'm standing outside the car with the doors locked, I press the unlock button 1x expecting it to unlock the driver door but it doesn't. It unlocks the passenger door. I press it again and it unlocks the other door.
I got the car from a used car dealership where it had been sitting for 4 years. They didn't want to put the time or money into it and pretty much gave it to me. I have it almost ready to drive but this issue is nagging and I'd like to get it fixed if I can. It seems like the door modules are reversed. The passenger side is behaving like you would expect the driver side to and vice versa. If anyone has any insight into this or needs more info, pls reach out.
Thanks in advance.
Michael
I have a 2003 C230 coupe. The driver door window switch will roll down the driver window but not the passenger window. I know the passenger window motor works because I can roll it down using the key fob. The passenger side window switch operates the driver side window (WTF!)... Also, if I'm standing outside the car with the doors locked, I press the unlock button 1x expecting it to unlock the driver door but it doesn't. It unlocks the passenger door. I press it again and it unlocks the other door.
I got the car from a used car dealership where it had been sitting for 4 years. They didn't want to put the time or money into it and pretty much gave it to me. I have it almost ready to drive but this issue is nagging and I'd like to get it fixed if I can. It seems like the door modules are reversed. The passenger side is behaving like you would expect the driver side to and vice versa. If anyone has any insight into this or needs more info, pls reach out.
Thanks in advance.
Michael
MBWorld Fanatic!
Joined: Jul 2017
Posts: 1,004
Likes: 148
From: Richmond, VA Metro Area
2005 C230 Sport Sedan-6 Speed Manual
I don't know the solution to your issue, but here's some insight that may help.
The electronic components in the W203 communicate over a CAN Bus. When you press a switch or the key fob, it sends a signal that is coded to provide a specific module an instruction. For example, when you press the window switch, it sends a signal telling the appropriate motor to move a window up or down.
This is a speculation, but I'm wondering whether a previous owner replaced the module in the passenger door with one from a driver's door. If it were my car, I would remove the door card on the passenger side and find the part number on the module. Search on that part number and determine whether it is the correct one for the passenger door in your car.
Another issue to consider is that your car is a "pre-facelift" W203. One of the areas addressed by the facelift was problematic electronics. It's possible that you have a defective module and replacing it with one from a 2005 or newer W203 will resolve the matter.
Good luck with your project.
The electronic components in the W203 communicate over a CAN Bus. When you press a switch or the key fob, it sends a signal that is coded to provide a specific module an instruction. For example, when you press the window switch, it sends a signal telling the appropriate motor to move a window up or down.
This is a speculation, but I'm wondering whether a previous owner replaced the module in the passenger door with one from a driver's door. If it were my car, I would remove the door card on the passenger side and find the part number on the module. Search on that part number and determine whether it is the correct one for the passenger door in your car.
Another issue to consider is that your car is a "pre-facelift" W203. One of the areas addressed by the facelift was problematic electronics. It's possible that you have a defective module and replacing it with one from a 2005 or newer W203 will resolve the matter.
Good luck with your project.
Last edited by KevinH2000; Sep 4, 2025 at 03:02 PM.
Thread Starter
Newbie
Joined: Jul 2024
Posts: 4
Likes: 1
From: Spokane WA
2003 C230K coupe
Update for the 1 or 2 people who may be following this (or someone 10 years in the future who has the same problem)
I used my code reader and checked the VIN. I ran that VIN through lastvin and looked at the options. It turns out that the ECU came from a 2007 C180 that was originally destined for Japan! Right-hand drive option. So now I just need to code it for Left-hand drive or continue to live with the quirks.
I used my code reader and checked the VIN. I ran that VIN through lastvin and looked at the options. It turns out that the ECU came from a 2007 C180 that was originally destined for Japan! Right-hand drive option. So now I just need to code it for Left-hand drive or continue to live with the quirks.
MBWorld Fanatic!
Joined: Jul 2017
Posts: 1,004
Likes: 148
From: Richmond, VA Metro Area
2005 C230 Sport Sedan-6 Speed Manual
I received a notification that you had updated this thread. I'm glad you were able to determine the source of the problem. I've used a clone of the MB Star system to code some functions in my car. If you have access to the system, it is not too difficult to use. I have not had to tackle your specific problem, but I had to activate the seat memory module after I completed a seat swap and added memory seats.
The 15th post in this thread shows the use of the MB Star System for coding.
The 15th post in this thread shows the use of the MB Star System for coding.
