Car intermittently will not start!

[Larkone]

@MERCMAN21 Google 'EIS module repair' and then take your pick from the (long) list of repairers

 

[RRmech]

I was thinking the same, and I was going to order a clutch pedal position switch as it was the cheapest option. And if nothing else, it would rule this out.
However, I was driving the car again this evening, after about 15 attempts to start it. What I did notice was the start / stop function is working fine, at least while I was driving it anyway, so this would suggest the CPP switch is working properly.
I still might order one anyway just to rule it out.
My gut feeling though is that it’s an EIS module problem. That’s not a cheap Mercedes part either.
Can these be repaired if needs be?
Or can a S/H module be programmed to the car?

Hi there , my CPP arrived today , so I decided to fit it , very easy job & it appears to have done the job , the car starts first time every time now , I know this won’t be the case for every intermittent start fault but always a good idea to start at the cheap end hope this helps .

 

[MERCMAN21]

Hi there , my CPP arrived today , so I decided to fit it , very easy job & it appears to have done the job , the car starts first time every time now , I know this won’t be the case for every intermittent start fault but always a good idea to start at the cheap end hope this helps .

This car is really really annoying me now. We’ve had the EIS module out, and checked and seems to be ok. Sent to a guy that repairs them. He took it apart and cleaned contacts and stuff, but there was no faults found. All seems ok with that. When that came back, we fitted it, and bypassed the clutch pedal position switch and it was still doing the same thing. However, I still might chance ordering and putting a new CPP switch in seeing as it’s so cheap and easy fit, and it seems to have fixed yours. It’s not really looking like the fault here though.
I’m at a loss now as to know what else to check. Is there anything else on the circuit that it might be? Or is it looking like a wiring issue?
Or possibly a software issue somewhere??
Anyone any other ideas??

 

[MERCMAN21]

Hey guys,

Just thought I should post a little update on this issue, as it might help someone else in the same situation, with the same intermittent non start issue.
Good news !! We seem to have got to the end of that problem, and the car seems to be starting ok for the past few months.
After checking the starter motor, CPP switch and EIS module, the problem turned out to be a simple 4 PIN relay.
We swapped out the relay for another relay and it has started every time since.
A simple cheap 2 minute fix is all it took. This has caused so many headaches though with trying to find the root cause.
I have attached some photos of the faulty relay.
I hope this is of help to someone in the same situation.

Thanks guys.

 

[AndySlade]

Typical Chinese Quality? I thought being a Hella it would be a quality item.

 

[DSK]

Very glad to hear you got to the bottom of your issue and what an annoying issue to have. (I have an intermittent all lights no crank/start issue with a w221 but I may not have the patience you had).


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[mioba]

nice one OP

 

[Jjarvis]

Which relay did you change? I'm having the same issue. Thank you

 

[DSK]

Starter relay I believe


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