JP70

Have a 2003 C240, wont crank at all, wont turn over with key, can feed 12 volts to fuse #52 and the starter will turn over, need help where to go next, thanks in advance for your help

Plutoe

Will the key turn in the ignition module, if yes check the front SAM, if no your key or ignition module is faulty!!

JP70

The key turns and powers everything just won't power the starter, what should I check in the SAM? That's the front fuse box under the hood correct? Fuse 31, 52 and 57 are all good. The relay doesn't click and I switched with other relays and no change.

Plutoe

On some VIN's there is a starting relay, on others the SAM itself provides the switch(relay) for the starter---post you VIN and I will check Sunday PM.

JP70

VIN#----WDBRF61J13A471703

Plutoe

It's incorporated within the front SAM---to confirm find someone with DAS to do a quick test!!

JP70

I can activate the starter by hand with the relay.

Glyn M Ruck

You need to check the whole process. Make absolutely sure that fuse 52 is fine & not corroded. The system also interrogates the CPS & temp sensor before start authorisation. Make sure those connections are good.

https://mbworld.org/forums/c-class-w...t-process.html

JP70

I checked the connections on both and they are clean, I just found out that the previous owner installed a cheap aftermarket crank sensor from autozone made by duralast. Will that cause a no crank condition?

Glyn M Ruck

It can if faulty. If the ECU thinks that the engine is already rotating it will not allow cranking.

JP70

Well it isn't shooting a code out for the crank sensor, so I don't know which way to go.

Glyn M Ruck

This is where DIY can get expensive because you can't try things from the spares dept. like a dealer can. CPS frequently does not throw a code but can still be bad.

JP70

replaced crank sensor again, no change, suspect front sam but would like some more input on how the sam works

Holmes5518

You really gotta get it hooked up to an SDS. Your issue is likely key or ignition switch related, and diagnosing them you really need to use SDS to test DAS. (Drive Authorization System)

jcgwapo

Hi there.. I have the same issue with my car with no crank no start.

What parts did you replace on your car?

Thanks

Drashley1

Similar Issues with my 2003 C240.

Car died while entering my parking garage. No crank.

After hooking a battery charger after about an hr......the car started no issues.

Drove the car to my mechanic and he checked the alternator and battery - no issues. He also drove it for a few days no issues.;

Took the car back after a few days and as I was driving back it died on the highway. After a few minutes it started and I returned it to him.

I had him check some key fuses and relays...all good.

Again it was there for a few days and he drove it on and off no issues. I took it back and after a few days same issues ....it had difficulty starting and then again died on the road. I started it after a few minutes and drove it to my mechanic and it died as i was entering his shop. He tried to start and again no crank and he immediately realized it was the AC Compressor.....it was getting heated or stuck........he loosen the bolt a bit on the compressor and it started right away.

AC Compressor replaced and so far no issues. This issue will cause the car to not crank sometimes if it is stuck or die on while driving as it ill get stuck and kill the engine RPM

Dr Ash.