rbhre

All this happen gradually, sometimes car would not start and then would engage with no problem. Two days ago, I came back home and since then I am dealing with the problem.
After the key is inserted then I am able with no problem to turn it all the way to the position that should start the engine. Battery is fully charged, I can play radio, open or close the car with central lock. Everything is functional; this is where I have suspected Faulty Crank Position Sensor. After replacing the sensor problem has not been solved, engine will still not engage, car will not start. When I was replacing crank position sensor, I have observed interesting think, that the old sensor was covered with oil; is that normal? Or something else is happening here. Now, I have find out that A common issue for not cranking at all is a small relay plate in the module box under the hood called K40
See picture
See also for reference attached picture below (please advise accordingly)
I should try swapping the relay #k2 in this plate as this is the starter relay, but commonly the relay plate itself fails internally. I was told that I should try removing the plastic cover on the underside of the relay plate to check the solder joints - this is what usually fails, supposedly there are people that have re-soldered with good success but I usually replace them as they are quite cheap. i don’t have the diagnostic scan tool available however so I am guessing however, I don’t think it will help much since the car engine is not running, or maybe I am wrong.
Please advise how to proceed this problem, I have open the box (check the attached pic) and I am still not sure how and what to disconnect and replace. Please help.
Best regards
Optional Information:
Year: 2000
Make: Mercedes-Benz
Model: c 280
Engine: V6

Already Tried:
I have suspected Faulty Crank Position Sensor. After replacing the sensor problem has not been solved, engine will still not engage, car will not start. When I was replacing crank position sensor, I have observed interesting think, that the old sensor was covered with oil; is that normal? Or something else is happening here.

xvvvz

I guess since it will not start there is no way for you to scan for codes until you can get it to Autozone or similar. Have you tried resetting the computer by disconnecting the battery for 30 seconds? Sometimes this will allow you to restart a car that is balking. Might give it a try. You will have to resync your windows plus sunroof and will need your radio code.

rbhre

I still didn’t figure out what is up, but I have eliminated many problems already.
So far I didn’t do much of swapping stuff just testing it.
In K40 relay plate I did swap starter relay… didn’t work. Car is still not starting. Now I am suspecting if starter solenoid “clicking” is telling me something that is located under the exhaust manifold. I am running few test with the probe in order to make sure… ok, so starter solenoid is not receiving any power (I did tested violet colored wire plug connector( A1 with pin 6) in K40 relay plate. Test failed)… now starter relay in K40 clicks when i turn the key to start (I have find out this one while I was running around with the probe in that section) so I did also test for the connection in plug C pin 3 - a large pink & red wire in K40 relay plate, this one has connection, no problem. Please, advice if anybody has any idea.

rbhre

Yes, I did. Each time I am swapping something then I am unplugging battery connection. Thanx very much for participating I really appreciate this.

rbhre

So I did check the diagram and since a large pink & red wire in K40 relay plate has connection, this cable is directly connected to starter relay pin numbered as 30. After probing for the connection there on plate itself were pin nr 30 goes, there was no indication for the connection which points on internal fault in k40 plate. I don’t know how to bite this, I don’t even have a soldering gun… I need to do more research, I will post result tomorrow. Any ideas are welcome and appreciated.
So I did check the diagram and since a large pink & red wire in K40 relay plate has connection, this cable is directly connected to starter relay pin numbered as 30. After probing for the connection there on plate itself were pin nr 30 goes, there was no indication for the connection which points on internal fault in k40 plate. I don’t know how to bite this, I don’t even have a soldering gun… I need to do more research, I will post result tomorrow. Any ideas are welcome and appreciated.

JUAN CASAUS

I'm having a similar problem with my 2000 C230...Where is the K40 relay located so I can check mine and see whats up with it

rbhre

I am not sure if this will be the same location but mayby
Attached pictures will help you to figure out after you see it. K40 is Mercedes designation for the small fuse & relay box (plate)in the picture. Let me know how you get on. K40 relay plate is the complete unit on the right hand side of the picture.
The starter relay is the black square relay on the end of this - try swapping this first (it should be a standard 4 pin relay).

rbhre

Here you go,
K40 (pictures)

K40 relay plate is the complete unit on the right hand side of the picture.
The starter relay is the black square relay on the end of this.

JUAN CASAUS

THANKS...WHERE DID YOU GET THE RELAY FROM?

JUAN CASAUS

I ALSO DISCONNECTED MY POWER SEAT BECAUSE IT WAS WORKING INTERMITENTLY AND IT SEEMS TO HAVE HELPED WITH THE STARTING ISSUE

JUAN CASAUS

OK...FOUND THE PROBLEM. I HAD A LOOSE CONNECTION AT THE BATTERY TERMINAL WHERE TH FUSE BOXES HOOK UP TO THE BATTERY SO IT WASNT CHARGING MY BATTERY AND WAS GETTING SO HOT IT WAS ALMOST WELDING THE METAL TOGETHER. I REPLACED THE TERMINAL ENDS AND IT WORKS LIKE NEW NOW. JUST CHECK YOURS YOU NEVER KNOW

daygobaker

My car wasn't starting, so I jumped the violet wire and had the starter activate....car was on the on position and it still wouldn't start...Right when I was going to give up...I gave the key one more try...Twisted it and the car started up....I don't know why but thats what I did...