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Mercedes Benz C200 CDi W204 2009 - Fault with multifunction unit - Fixed #

Posted by Job Gevers on November 9, 2016, 12:17 pm

Year of Manufacture *: 209
( Optional ) Engine Code or CC: 2.1

Hi,

Just wondering if anyone has come across this before.
No communication with any control units, indicators not working, wipers coming on randomly etc.
Basically, all functions controlled by the multifunction unit that is part of the under bonnet fuse box are not working but engine starts and runs but radiator fans are on full.
One mirror indicator is missing and one front fog light is damaged.

Cheers,

Job

Re: Mercedes C200 CDi W204, fault with multifunction unit

Posted by andrew young <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5148' width='330' height='300' border=0 style='border:none;'> on November 9, 2016, 8:07 pm, in reply to "Mercedes C200 CDi W204, fault with multifunction unit"
Andrew Young

I would check fuse box for any blown or missing fuses.I have seen cooling fan issues on these caused by faulty pressure switch on the a/con system.May or may be not related.

Re: Mercedes C200 CDi W204, fault with multifunction unit

Posted by Kevin Apps <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT2589' width='330' height='300' border=0 style='border:none;'> on November 9, 2016, 9:31 pm, in reply to "Re: Mercedes C200 CDi W204, fault with multifunction unit"
Kevin Apps

Job

"radiator fans are on full."

yes that is only a fail safe.

Do you have a WD.

Kev

Re: Mercedes C200 CDi W204, fault with multifunction unit

Posted by Job Gevers on November 11, 2016, 8:17 am, in reply to "Re: Mercedes C200 CDi W204, fault with multifunction unit"
Edited by board administrator November 18, 2016, 11:39 am

Sorry for my ignorance, what is a WD?

Because the problem is intermittant i am having difficulty determining if it is the fuse box/multi function unit at fault or something else.

When the car starts communicating again all that comes up in most control units is voltage or communication faults.

At the moment looking at some wiring diagrams, i am assuming that there are 4 relays that power the multi function unit. I will see if changing about with those relays the car starts working again...

Re: Mercedes C200 CDi W204, fault with multifunction unit

Posted by Kevin Apps <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT2589' width='330' height='300' border=0 style='border:none;'> on November 11, 2016, 9:19 am, in reply to "Re: Mercedes C200 CDi W204, fault with multifunction unit"
Kevin Apps

Job

"When the car starts communicating again all that comes up in most control units is voltage or communication faults."

Posting the codes and the reader should be basic posting info.

"At the moment looking at some W iring D iagrams"

Kev.

Re: Mercedes C200 CDi W204, fault with multifunction unit

Posted by Job Gevers <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5524' width='330' height='300' border=0 style='border:none;'> on November 11, 2016, 1:52 pm, in reply to "Re: Mercedes C200 CDi W204, fault with multifunction unit"
Job Gevers

:-) Sorry, must be losing my English.

Yes I do have some wiring diagrams for this car but i don't have any CAN protocol definitions to allow me to check the bus properly when the fault occurs. Has anyone had their Canalyzer on one of these MB protocols and done some labeling?

Swapping relays about seems to have sorted the problem (for now).
I was stupid enough to do a global fault code erase before noting everything down.
I expect the problem to re-appear in due course and i will make sure to save the fault codes.

Meanwhile, has anyone had problems before with these relays, MB part no. A0025428319 and A0025428719?

Cheers,

Job

Re: Mercedes C200 CDi W204, fault with multifunction unit

Posted by andrew young <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5148' width='330' height='300' border=0 style='border:none;'> on November 11, 2016, 5:19 pm, in reply to "Re: Mercedes C200 CDi W204, fault with multifunction unit"
Andrew Young

I think there was a tech bulletin about
these relays featured in the IMI magazine,sponsored by autodata.Faulty relays are not unknown on certain model years of the 204 range.

Re: Mercedes C200 CDi W204, fault with multifunction unit

Posted by Job Gevers <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5524' width='330' height='300' border=0 style='border:none;'> on November 13, 2016, 11:53 am, in reply to "Re: Mercedes C200 CDi W204, fault with multifunction unit"
Job Gevers

Thanks Andrew, I've ordered the relays anyway, just to make sure, or to have them in stock.

Fixed #

Posted by Job Gevers on December 8, 2016, 7:18 am, in reply to "Mercedes Benz C200 CDi W204 2009 - Fault with multifunction unit #"
Edited by board administrator December 9, 2016, 1:11 pm

I replaced the system relays on the under bonnet fuse box, even though i couldn't fault time every time i tested them.
But the intermittent drainage of the battery when i wasn't looking seemed to point towards these relays.

The car has been fine for 2 weeks so i suppose i can call it fixed...

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