W211 Heated rear screen not working

[RCS]

Seeking some advice please.

We have a W211 E Class 55 reg'd. We've had it since the early summer, but only just now needed the heated rear screen which isn't working.

• Switch on dash board lights up and goes out after a period, so assume there's a timer on it which is working.
• Checked fuse (F010 in boot?) thats fine
• Tried to check wiring onto rear screen, managed to pull back some trim. Seems to be some braided strip with multiple solder points to screen on each side - checked and no voltage across them.

It was bought as a MB Approved used, so I am sure this will be covered under that warranty, but as dealers are not close and not convinced of their capability (a long story), looking to see if there might be a quick simple fix to save the aggro!

So any ideas or known issues?

Also trim panels on either side of rear window seem a pain to get properly clipped back but cannot see clearly how they fit as they are not detached, any guidance welcome.

 

[BlackC55]

I think that the power is supplied by the rear SAM module.

If the fuse is ok and the wiring is good I would be looking at that.

 

[Braincrank]

I had an issue with the intermittent wiper setting and rear windscreen heater not staying on. Got a new relay and both issues are history (-:
Edit to mention it is on a 1989 124.

 

[RCS]

Thanks BlackC55 - if its the SAM then I'll leave to the Dealers to sort/invesitgate.

Braincrank - did wonder about a relay, but don't know where it is and who easy to remove and check. There's some on the rear fuse board, do they just plug in? Maybe it could just need removing and reseating, but don't want to be messing about with ones which are nothing to do with the rear screen - if it ain't broke don't fiddle!!

 

[Braincrank]

Hey RCS, sorry for late reply . Yes it's the one behind the fuse box . I think there are two or three , if I remember correct.
I bought the relay in Germany and the part no is MA201 821 02 47 €34.-
But that was for my 124
It's very easy to change. Have you got a work manual? Otherwise take the lid of the fuse box and you will see a few screws. Undo them and the lid of the box behind the fuse box comes off and give you access to the relays.
Pull it out and pop the new one in. Provided you know it's the cause of you problem

 

[RCS]

Thanks Braincrank.

If it still didn't ahve the MB used car warrenty I'd be in there, guess I'll see what they find. Mind you las time they couldn't even mend the vanity lights over the sunvisors, and I ended up doing it so you never know!

 

[Braincrank]

I went to a Merc place while I was in Germany and explained my problem with the intermittent wiper not working and not knowing if it was the switch or anything else. The switch would have been more expensive and more work to swap.He asked straight away if I had issues with the rear windscreen heater too. I was quite amazed about it. He obviously knew what he was talking about ,
got me the right relay and that was it.
I've also got a good old Haynes manual that has helped me a lot over the years

 

[mattc]

thread revival. I have the same problem as the OP. I have swapped the 40 amp fuse and the rear relay with known good ones (they work fine in the wife's car so I know they are good). Are there any other relay etc I can swap before I start stripping out linings to find broken/detached wiring (I am assuming not ALL the elements in the window can be broken).

Also, don't know if this is related but the 2 x 12v sockets in the cabin do not seem to work either.

thanks in advance