W202 Rear Power Windows Mystery
08-24-2024, 02:27 PM
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W202 C240 1998
W202 Rear Power Windows Mystery
Hello all. First time post due to being absolutely stumped with a rear power window issue on my 1998 W202 C240 Elegance.
Really hoping there is some MB guru out there with a silver bullet answer to what has already baffled at least 3 MB mechanics.
I'll try keep this as short as possible.
The rear power windows weren't working when I bought the car, so unfortunately I don't know what caused them to stop working.
Front windows work absolutely fine, and all other switches on the centre switch console also work fine.
Rear door switches illuminate when I turn the car's lights on, so there is clearly communication happening to the rear motor modules (because I believe the power for the switch lights come from there).
There is also power at the rear windows when I check the permanent live and earth that goes into each motor module.
The first thing I did, based on forum discussions, was disconnect one at a time then try the other one to see if maybe a faulty module was screwing up both - no luck.
I then checked the CANBUS connector in the passenger door sill. Was quite dusty, but otherwise no sign of damage or corrosion. Cleaned the whole thing anyway. No luck.
Then I bought two spare motors from a second-hand parts shop. Although someone wrote A-class on those motors, they look precisely the same and the shop said they are interchangeable (views on this?)
Anyway, you've probably guessed neither of them worked when plugging into the rear door wiring (exact match on the fitting - which supports shop saying they were interchangeable).
Then I found a different motor from a 2000 C-class, albeit not a C240 but surely must be the same, tried it, also didn't work, so I didn't buy it and gave it back.
Then took the car to MB dealership who diagnosed it and said the centre switch console was the wrong one for the car and that was probably the cause.
Indeed when I took it out, the part number was not as per the Mercedes WIS listing.
This is where it gets fun. There are three part numbers listed for those switches on WIS as follows:
1) A2108208410 (Replaced by A2108214051)
2) A2108213951
3) A2108214051
I managed to get hold of a second hand A2108213951 above and it worked fine for the front windows and mirrors, but still not the back windows.
Tried the "A-class" motors again at the back with the new switches, in case it was both the motors and switches that were the problem, no luck.
So I'm now totally stumped and really hoping someone has a bright idea for me.
As I understand it these switches work on very sensitive frequency changes to send signals to the window motors, so could it be a compatibility issue between the front console and the motors which look identical but could be from a different model?
If that is the case it's just weird that the rear switches would illuminate when I turn the car's lights on. And also that MB would change the frequency between such similar parts for similar era vehicles.
Anyway, highly confusing and frustrating. Holding out for a Hero to save me here.
Really hoping there is some MB guru out there with a silver bullet answer to what has already baffled at least 3 MB mechanics.
I'll try keep this as short as possible.
The rear power windows weren't working when I bought the car, so unfortunately I don't know what caused them to stop working.
Front windows work absolutely fine, and all other switches on the centre switch console also work fine.
Rear door switches illuminate when I turn the car's lights on, so there is clearly communication happening to the rear motor modules (because I believe the power for the switch lights come from there).
There is also power at the rear windows when I check the permanent live and earth that goes into each motor module.
The first thing I did, based on forum discussions, was disconnect one at a time then try the other one to see if maybe a faulty module was screwing up both - no luck.
I then checked the CANBUS connector in the passenger door sill. Was quite dusty, but otherwise no sign of damage or corrosion. Cleaned the whole thing anyway. No luck.
Then I bought two spare motors from a second-hand parts shop. Although someone wrote A-class on those motors, they look precisely the same and the shop said they are interchangeable (views on this?)
Anyway, you've probably guessed neither of them worked when plugging into the rear door wiring (exact match on the fitting - which supports shop saying they were interchangeable).
Then I found a different motor from a 2000 C-class, albeit not a C240 but surely must be the same, tried it, also didn't work, so I didn't buy it and gave it back.
Then took the car to MB dealership who diagnosed it and said the centre switch console was the wrong one for the car and that was probably the cause.
Indeed when I took it out, the part number was not as per the Mercedes WIS listing.
This is where it gets fun. There are three part numbers listed for those switches on WIS as follows:
1) A2108208410 (Replaced by A2108214051)
2) A2108213951
3) A2108214051
I managed to get hold of a second hand A2108213951 above and it worked fine for the front windows and mirrors, but still not the back windows.
Tried the "A-class" motors again at the back with the new switches, in case it was both the motors and switches that were the problem, no luck.
So I'm now totally stumped and really hoping someone has a bright idea for me.
As I understand it these switches work on very sensitive frequency changes to send signals to the window motors, so could it be a compatibility issue between the front console and the motors which look identical but could be from a different model?
If that is the case it's just weird that the rear switches would illuminate when I turn the car's lights on. And also that MB would change the frequency between such similar parts for similar era vehicles.
Anyway, highly confusing and frustrating. Holding out for a Hero to save me here.
