W210 320cdi Estate Rear Wiper Not Working

[Dog man]

Hi all

I'm just hoping fora bit of W210 specific things to look into other than what I may already have tried - the problem - I have the aforementioned car in and for the life of me I have been unable to find out why the rear wiper isn't working.

So far I know: the motor works, the wiper runs if I jump the wiper motor relay, there is power at the motor plug (obv else it wouldn't run) The dash switch doesnt light up or work at all - have opened switch up, inspected and re flowed all solder joints. The PSE unit looks like it could be new, it's certainly not corroded in any way shape or form. The rear wiper fuse is not blown (40a, would be something). No voltage there either.

The only thing wrong with the car is fuse 11 in the engine bay keeps blowing (rear 12v socket, seat adjustment, rear reading light, anti theft system - SE) but all of these things work as they should. I've tried disconnecting everything listed for fuse 11 but it still blows.

Battery compartment is dry, boot area is dry.

I've been searching for hints and information and read elsewhere that the dash switch sends a message via CAN bus through the PSE unit. Wondering if this was indeed a new PSE unit, could it be for a saloon? It looks brand new rather than second hand. The foam around it is dry also.

Only other time I had a head scratcher like this was a W220 which needed I think front and rear SAMs replacing due to rust. This reminds me of that because in addition to the above, I cant connect to the engine ECU but can access some other bits (TCM springs to mind)

I do have other ideas to pursue and things to test I'm just reaching out for some additional minds to help me along


Thanks in advance.
Steve

 

[mattkh]

........the only thing wrong with the car is fuse 11 in the engine bay keeps blowing. Thanks in advance. Steve

When does the fuse blow, as soon as you put it in the socket? When you turn the ignition ON ?? When you touch some control ??

 

[EmilysDad]

.....

The only thing wrong with the car is fuse 11 in the engine bay keeps blowing (rear 12v socket, seat adjustment, ....

I know that a 5 pence coin is a nice fit in a cigar socket .... not easy to see either.

 

[Dog man]

Appreciate the replies guys thanks

Fuse pops soon as ignition switched to pos 2. Note this is not the wiper fuse but I have a hunch it might be related.. by way of a corroded SAM unit possibly.

Cig lighter all clear - it's been removed to dismantle the centre dash in order to get to the wiper switch. Also rear 12v socket has been unplugged and checked also.

 

[Blobcat]

I know that a 5 pence coin is a nice fit in a cigar socket .... not easy to see either.

Had that in my VW Caravelle, PITA to get back out as well

 

[mattkh]

........ the wiper runs if I jump the wiper motor relay,.......Steve

How were you jumping the relay?
When you were jumping the relay, was there a working fuse in the socket?
When you were jumping the relay, was the ignition ON ?
Any chance of a few pictures of the relay, showing the pins and the diagram drawn on it.
Thanks.

 

[Dog man]

Hey bud. By removing the relay and jumping the pins that switch the power from the power / loom in, to the motor. I forget the numbers now. So I was basically acting as the dash switch. Whats missing is the signal from the wiring loom / car to do the same thing.

I don't think it's the relay because I tried a spare and tbh it looks brand new like I'm following someone else train of thought.

Thanks again chaps, I will update

Right, got an OM642 in a GLS320cdi no less for oil cooler gaskets, joy.

 

[mattkh]

,,,,,,,,Battery compartment is dry, boot area is dry...Steve

Have you checked the back of the relay box for any break or moisture. If it is a big task, then you can use a low setting on a hair dryer and blow on it.
Is the fuse that blows and the wiper relay in the same box ?

 

[Dog man]

Thanks Matt, relay is on the wiper assembly on the tailgate. No the Fuse that blows is in the engine bay.

If any pf the SAMs are corroded internally, it could explain this seemingly bizarre behaviour.

Body to tailgate loom was a thought but there is power at the wiper motor plug so my thoughts aren't going there just yet.

Another clue cant remember if I added it was that I cant connect to the engine ECU via diagnostics but I can other modules.

 

[Dog man]

Hi guys just an update that I'm still chasing this. Tried a front Sam (was next to nothing) but no joy.

The tailgate wiring is OK but does run past the rear seats as does the rear 12v socket wiring - the rear 12v socket is part of fuse 11 in the engine bay fuse box and is the only element of fuse 11 that doesn't work. I wonder if something is wrong with the loom in that area, this is my next thing to Check.

Also found car belonged to a member here!