MB C320 cdi 2008

[gez50]

I've owned the above car since 2012 and for the past 3 years have experienced intermittent starting issues as follows:

1. It started with dashboard messages saying 'run flat inoperative' - car does not have run flat tyres - and fails to start. Dash lights on but no power. Keep trying and it does eventually start, particularly after leaving for a few minutes. On occasions the fan comes on, even though car won't start and this seems weird with the car not running.
2. When this first happened it settled itself and stayed clear for about 2 years, but has reared again in recent months.
3. So far car has been checked by local garage who couldn't find anything other than needed a new battery, which it didn't as it turned out. The problem was not resolved as it failed to start again the following day.
4. The issue has continued off and on ever since.
5. Mercedes specialist checked it with the machine used by MB to try to find the problem. He checked various points in the car and nothing showed up. He is of the opinion that it could be the ECU, but without it showing this as an error and the car not playing ball with not starting whilst he was here he is unable to be sure.
I am wondering if anyone else has experienced this problem and could suggest a resolution. I am reluctant to pay MB for their services at this point, especially as they were not interested when the problem arose initially.

 

[mersum1es]

Sounds like voltage/grounding problem (run flat trigger, fan at full blast), but where originated can't say... grounding probelem/broken wire may be PITA to find, or ECU inner problrm to pinpoint.

Are all ecus without trace of water/corrosion, earth straps in good contact?

 

[gez50]

Thank you for your reply.
What you have said sounds feasible.
The Mercedes specialist I use checked the ECU when the problem first arose and discovered some green inside the male connector pin inside the M cover of the ECU, just on the one pin. He sprayed it with a suitable spray which appeared to resolve the problem for a while, but then it came back. On the recent check to try to find out the problem he found the pins to be clear of any signs of damp. He also checked along both sides of the floor of the car to ensure all connections there were clean and dry and has found no more evidence of damp/moisture.
He feels it could be the ECU at fault, but while it is not malfunctioning in his presence he cannot pick the fault up on his computer.

 

[Smiley]

Electronic ignition switch?