Hi, hope someone can help as I am pretty stumped!

I have just bought a 2004 C180 Kompressor and the steering wheel controls (horn, trip computer, telephone and stereo volume?) do not work. I am pretty handy usually and decided to buy it thinking I would be able to fix it! FAIL so far

Despite the SRS light NOT being on, I thought the squib / clock spring would be the culprit... I'm pretty sure these controls aren't fused, but checked all of them anyway to be sure (in all three fuse boxes, in car, engine bay and boot) and after satisfying myself it wasn't a fuse, forked out £250 for a new clock spring from Mercedes.

I have just fitted the new one, but to my surprise, still no horn or controls. The fact that the SRS light wasn't on should have been a clue to the fact I was barking up the wrong tree, but hey-ho!

Anybody please able to offer any advice or suggestions? Is it possible that the airbag and control unit itself is to blame? Is there a control module that the clock spring feeds into?

Any suggestions other than clock spring or fuses sincerely appreciated.

Thanks,

Mike

 

With horn, I would think a bad connector somewhere. However, they could be unrelated, the steering wheel switches are known for failure issues. Check the sticky above on DIY things, there is a step by step on repairing them.

 

Thank you for your reply. I'll have a look at the sticky if it turns out to be the unit.

I've got an auto electrician coming out on Monday. Hopefully he'll be able to tell me where the signal break originates and I can go from there

 

hi,i have the same problem with my c220 cdi,have you fixed it,need some help,many thanks

 

Hi there, I haven't solved it as such, but think I now know the cause and solution... Basically I have decided to sell mine as spares or repairs on Ebay as fed up with it and the cost of MB parts!!

The auto electrician identified the fault as being in the airbag/multi function steering wheel control module. I took the airbag unit apart and found the control unit (a motherboard in a plastic protector that feeds from the clock spring into the steering wheel control switches and horn switches) and tried to source a new one. Surprise surprise MB don't list it as a separate part and have told me that I need to buy the entire airbag unit at a cost of £500! This is despite the fact I advised them my airbag is good and I have no SRS light on!!

If yours has the SRS light on, chances are its your clock spring, but if the sympoms are identical to mine, SRS off but no horn or controls then I'm afraid it's a new airbag unit for you too.

Hope this helps.