I have a 2003 c320 4 matic. For the past two months the power seat on the driver side has been working intermittently. First the fore/aft (front back sliding motion)would not work. And sometimes using the control for the fore/aft would move the headrest only (??). All other controls would work for the seats, just not the fore/aft. Then the other day, my husband moved the control back and it magically worked- but then got stuck in that position and now I am unable to move it back to 'my' position. And to top it off, now NONE of the controls for the seat work. I've checked the fuses, all good. I've also checked the connections under the seat- all tightly in place. Last night my husband took apart the door panel and checked the actual switch on the door to see if it was getting power. It is. The only thing we can think of (after searching the forum) is that it could be the CF (Configuration Feature) Relay K24 located in the trunk OR the SCM is bad. My husband took out what looks like the K24 relay (not sure), but didn't open it up to check the internals and solder joints (we werent sure if this was the K24).

I called the mercedes dealership today to order the relay- but they have no idea what a CF relay is (can you believe that!) and they need a part number.
Can someone help me here? Desperate at this point as I am driving with a pillow to reach the pedals.....

I appreciate your help in advance.

Thanks!

 

It may be the switch itself.. I had the same kind of thing happen to me not too long ago. Got the switch online, installed it (fairly simple) and it worked again.
Did you have the dealer diagnose it?

Because if it is something more simple, it'll probably be a lot cheaper than having to buy the whole switch.

 

Thank you so much..

The dealer charges $95hour for diagnostic..so I thought I would save some $ and troubleshoot it myself. It's out of warranty

 

Totally understand about the diagnostic fee.
I got my switch from mercedespartscenter.com. They're the cheapest ones I found on the net and they don't charge a lot for shipping. I'd give them a shot if you're looking to save some cash.

 

I'm having a hard time fixing the passenger side power seat back rest, headrest and front seat U/D. The memory doesn't work either. Cleaned all the motors and applied 12VDC directly to the molex connectors Brown, Black and Green and all move back and fort as they should. The hall effect sensors measure about 5000 ohms but don't know how to test them.

All the the digital signals from the seat control switch 203 820 72 10 are present (took it apart bcse I din't have the schematic)and even replaced it with the pigtail jumper, no help. I also replaced the door control module 203 820 14 85, Q10 version? With a used eBay part and no luck.

I found an old stock, brand new SCM for $70 on ebay, 211 870 47 26, it made no difference.

F1, F2, 30Amp are ok and so are all the fuses and memory power to the SCM. I tried resetting it, but no luck. The backrest and Headrest won't move. When I test for voltage at the back of the Molex for the back seat while the switch is active there is no voltage coming from the SCM.
HELP!