Hi, I keep having issue when the weather is cold every morning. Car don't want to start as everything works however preglow lights don't lights and cooling fan blast full speed. After 10-30 minutes try than preglow comes in and engine starts. It will run all day no problem, only in the morning will give me hard time.

I have searched all forums in UK and US and seen many E Class had similar issue but some reason forums ended without solution- perhaps they gave up.

STAR don't capture this electrical fault as EIS keep resetting the fault when ignition turned off and on again. Due to issue I can only see ESP/ ABS fault on display however this is only failing due to previous fault and only stays there for a minutes.
I have replaced EIS and the key, all fuse box and relay checked and some relays replaced. I have spent £2650 for this fault and still not resolve. MB technician and my local garage have no idea how to resolve this.
I also runout all my ideas and my money. Please help if you can...

Many thanks in advance, Sezai

 

Without having the wiring diaghrams from your description the glow plugs aren't lighting, so I would check that circuit. My diesel truck had the same issue and the relay powering the injector drive module that triggers the injectors had failed. A $4.00 part solved my problem but the initial problem solving indicated a $1000 part. IF the plugs don't light up look at the wiring for how power is delivered to the plugs. (relay failure) then if you have power to these parts check the tempurature sensor to see if it has failed. The temp sensor is normally just a thermistor that changes resistance with temperature, but the mfg gives it a fancy name to throw you off. Resistance changes with temps. It might be defective also. Sorry I can't be more help but I don't have wiring schematics for your car.

 

Hi, Thank you for replaying. I will check tomorrow fuel relay and wiring. In the mean time attached wiring diagram but this diagram is way above my knowledge.
I believe my fuel pump relay appears hot when the car is running - is that normal?

https://mbworld.org/forums/attachmen...m-sheet-1-.pdf

 

hi all, Update after long investigation and spending more money. Actual issue is when the temperature is cold about 2 Celsius or below then car won't start.
Which is no cranking and no preglow lights on the dash but everything else seems ok. after first attempt to start the car ESP and abs faults on the dashboard and cooling fan full blast works - when the key switched off and on then reset it self no faults for 10 seconds then faults again - in the mean time no cranking - could switch ignition key on and of between 10 to 50 times before the car start working. This is totally how cold the car than longer the start issue - could be 5 or 45 minutes try over and over again... So this is the problem...
When car start working everything is ok and runs without fault.

Spent nearly £3000 for wasteful investigation done by Mercedes and some local garage and solution is nil... Because of the fault that is not visible to Star diagnostic and these days tech are automated and have small knowledge about car - start tell them what to do...

During investigation: All replaced - Ignition switch EIS and two new key with programs. New gate way ZGS, front and rear Sam all opened and checked, most wiring and pre-glow, starter all checked! Solution is nil, nil, nil...

I told the mechanics all the way through for them to focus temperature relation and ECU control - it seems I am being ignored.

SOLUTION: Faulty ECU... I spend two week and study about car communication system. I can't say I know it all but make me to focus to ECU and I heat up just the ECU self - guest what car works when the ECU heat up. That is why not working when the temperature is too low. I don,t know why? - it could be something faulty inside and current not passing through when is cold.
I did open ECU and look inside but all clean visible spotless.
I don't want to spend another £1200 for it however I purchased two small PTC
heater - they are 5W and 20W for heating ECU before startup. So it is temporary fix - I will try it this morning.
If you have similar issue check and heat your ECU first before spending silly amount to no skilled Merc techs.
By the way if anyone know the temperature relation in ECU please let me know... thanks Sezai

 

merc b class engine will not turn over how can I check wiring to starter with out takeing the engine out

 

I finally discovered why my 2005 E320 CDI won't crank over when temperature goes down to 50's especially in the early morning. It was the ECU or it's also called the CDI Module. The symptoms are no preglow light comes on and no crank over but all dash lights are on, and if you leave the ignition in the ON position you'll hear the radiator fan turns on at full speed and the ESP message comes on. To pinpoint this problem, get a heat gun and remove the electronics cover under the hood driver side and warm up the ECU gently, then try to start the car after a few minutes. If it starts, then that's your culprit. I purchased a used ECU from ebay and I had it reprogrammed to my car and problem was fixed!

 

Thanks for that info.

 

Dear DRMD,

Don't Listen to what the dealer say because they don't want you to get your car fixed the easy way and they want to make tons of money off of you. I bought a used ECU off ebay and a local MBZ shop passed me a phone number of a guy that reprograms ECUs for mechanic shops. This guy normally charges $250 for this kind of job. I live in SFO bay area in California, so I can pass you the guy's number if you're near by. You can also contact one of ECU repair services on ebay and see if they'll reprogram the donor ECU for you. Good luck!