C200 Estate W204 Rear Wiper not working

[Oingles60]

Hi,

The rear wiper stopped working a while back. The washer still works, but the wiper doesn't move. The indicator for the rear wiper lights up on the dash, as normal. I found the fuse and checked it (13). I'd like to check the relay, but I'm not sure which one it is; does anyone have a relay list or diagram? I stripped down the tailgate and took the motor off. It runs if you apply current directly to the connector on the motor. With the motor remounted, I'm measuring current only on the middle pin on the connector. This is intermittent, which I assume is fine as it's an intermittent wipe. If you use the wash function, it shows continuous current while the wash function is operated. No current at any time on the other two connection pins. We tried a new motor and that was the same. I'm going to MB for a service next week, so I might ask if they can read the CAN Bus codes; does anyone think that would help?

Any thoughts would be appreciated. PS The VIN is WDD2042011F647770

 

[lukejr]

Hi,
I've the very same problem all the same for me. What was the outcome at the Merc garage, was it the relay?

Thanks, Luke

 

[Corty]

It the motor runs where there is power applied to it, if you have no power to the motor you could check the wiring loom between the body and tailgate for continuety, this is a very popular cause on hatchbacks and estates that have these type of failures, the wires can become broken from flexing all the time. It would be my place to check or get checked.

 

[lukejr]

Hi Corty, thanks for the reply. What should I be reading from the 3 pins on the connector from the car with a multimeter? And what is pos/neg, or is neg the body of the car and I just go through each pin?

To get the motor working on it's own, which of the 3 pins do I apply the 12V to (pos/neg). I'm fairly handy with electronics but only getting used to how cars do their setup with neg normally being the body of vehicle.

Got the map of the wiper wiring loom from Haynes manual, see attached.


Thanks again, Luke

 

[Corty]

I am sorry but I think I gave the wrong impression of being in the know here. I was just generalising with a comment cause of that type of fault. I don't know if these cars allow the wiper to operate when the tailgate is up but if it was I would try wiggling the the plastic sleeve that holds the wires in that go into the tailgate whilst the rear wiper is switched on and see if its a broken wire, it may start to move if you can cause them to touch. But more likely with it being a very technical car it's probably not going to be that simple. I'm not a wiring expert but it looks like it goes through the rear Sam, so maybe a plug in of a diagnostic scanner might shine some light. Let us know how you get on.