2005 C200 CDI intermittent non-start.

[Drum]

As per title every now and then (infuriatingly unpredictable) the car won't start. Usually when engine warm but can't say for certain and don't really want to tie this as the reason. Symptoms: Key to position 2 and all dash lights come on as per usual, except on occasions when it won't start the heater light will not have come on at all. Then I know it won't start. Leave it for a couple of hours and try again; in all liklihood it will start. I will know in advance becasue the heater light will come on and go out as per expected.

I have checked the three fuses identified as start enable 31, 52 and 57 (If I recall correctly) and have checked the functioning of the starter relay. All sound. Are the glow plugs on the same circuit or if a different line then could you let me know the appropriate fuses or relay to check. If they are on different circuits the I would suspect SAM or some other problem closer to source before the circuits branch off but let me know what your think please. And thank you very much for any help you can give. I want to rule out electrics if possible, before going to blame the actual starter, which I really don't think is at fault.

 

[mersum1es]

Warm start problems are very often crank shaft position sensor (CPS) related, but it should not prevent glow plugs to heat...

I have a dim memory about the case where has similar no glow plug light - no start problem, but cannot recall outcome failing glow plug relay box should not cause total no start.

 

[E270 Owner]

Glow plugs have separate feeds to them and can be tested at the point of connection for timed live feeds.

You dont mention if the car turns over and wont fire up or it wont turn over at all.

 

[Drum]

Apologies - should have pointed out there is no attempt to turn the engine over during the non-start episodes, it appears no power is getting to the starter.

 

[Drum]

Warm start problems are very often crank shaft position sensor (CPS) related, but it should not prevent glow plugs to heat...

I have a dim memory about the case where has similar no glow plug light - no start problem, but cannot recall outcome failing glow plug relay box should not cause total no start.

I read something about that too (on a sprinter) and a replacement SAM was the solution on that occasion, if we are referring to the same event. I really hope it is not the SAM but again with these things that are intermittent it can be very difficult to pinpoint the cause when the car is working. No codes stored or anything to go on.

 

[BlackC55]

It could be a faulty ignition switch. It needs a Star or its just guesswork.

 

[E270 Owner]

Apologies - should have pointed out there is no attempt to turn the engine over during the non-start episodes, it appears no power is getting to the starter.

I thought that's what you meant


If you have a spare key try that

As BlackC55 posted MB Star session is recommended.