Occasional Non-Starting C200.

[mobi]

I have a 1998 C200 auto which is really bugging me. Just once in a while it will not start, after trying for several minutes trying, including locking/unlocking it will suddenly start as if nothing was wrong and will keep starting without problems. My question is this, what happens when the immobiliser is working,? will the engine still turn over and not fire up , or will the engine not respond to the key at all ? I feel it may not be the immobiliser and I may be looking in the wrong direction. Can anyone advise please??

 

[television]

Does the starter motor spin when it will not start

 

[mobi]

Yes, to all intents it behaves normally,you turn the key, it takes over from you and turns the engine over for about 5 secs then switches off , not a hint of firing up !.

 

[television]

I am off to bed now, but the immobilizer does operate several functions the starter cut off is on a separate relay,,that's why I asked.

Will talk some more tomorrow

 

[mobi]

I decided to renew the brake switch as these are reported to cause problems and they are quite cheap, on checking the old switch I found the circuit on the large contacts on the switch that work the stop lights work fine but the circuit on the small contacts would only switch if I pulled the actuating plunger right out, the spring return was not enough to work the switch. I'm not sure what this smaller switch controls, could it interfere with the running/starting ?? Anyway, I'm taking it out for a run with er indoors this weekend to see if it has improved,God, I hope it's OK !!

 

[Cole@MBS]

Sorry to say but the brake light switch has nothing to do with the starting of the car, this is more to do with the ESP and locking control of the selector module!

 

[mobi]

Tried to take it out for a run but on starting up it misfired for a few seconds then started "dieseling",revving up and down without touching the throttle ! revving up cleared it but I lost confidence and decided to take the
astra out instead.! will now look at crankshaft pos; sensor and camshaft sensor unless anybody has a better idea of what's going wrong.

 

[anyweb]

have you checked your OVP *over voltage relay*

if the solders get wobbly it can cause odd effects such as the car seemingly accelerating itself, cleaning this OVP relay can help

the ovp is a big square relay with a fuse on the top near the electrics of the car opposite side to the fusebox at least on my c220

cheers
anyweb

 

[mobi]

Unfortunately my car does not have the OVP relay,I searched for it but had to give in and ask Mercedes where it is and was told on this model it is no longer fitted.

 

[mobi]

Latest report, changed the crankshaft position sensor, (which was great fun to do,!!!) and all now appears well, thanks everybody for your time.