Hello... I know this is a well documented issue with Mercedes cars, the dreaded no start. I've been all over the web, but I am still not certain which path to take. This is a 2011 C300.

Over the past several months I had an issue where I had to turn the key twice to get the car to start. The car would crank, but not start. I thought I had a fuel pump issue, but the pump checked out okay. I hopped in the car about a week ago and the car wouldn't turn over. There was no crank, just silence. I pulled out my multimeter and checked all the fuses. All the fuses checked out okay. Next I checked the starter relay. There was power at the relay (and I could feel/hear the relay actuate) so I then went to starter and found power reaching the starter. I pulled the starter, had it tested, and it failed (too much amp draw, slow turning). I replaced the starter and the car started perfectly about 5 times and then it wouldn't turn over again (no crank). I checked the starter relay and now I don't have power at terminal 30 (should be constant power, right?). When the key is in the off position, there's no power at any terminal of the starter relay. With the car in the ON position, I only have power at terminal 86.

My iCarsoft scanner reports the following codes:
Codes under Adaptive Brake (Chassis CAN BUS)
5945 - Control unit N30/4 (Electronic Stability Program control unit). internal fault
7208 - Check codings in control module Engine control module
6108 - No CAN message was received from control unit Engine Control Module
6106 - No CAN message was received from control unit Engine control module or N15/3 (Electronic transmission control control unit).
5001 - Control unit N30/4 (Electronic Stability Program control unit). internal fault
5060 - Power supply A7/3m1 (High pressure and return pump).

Code under Driver Side SAM
U001988 - Interior CAN communication has a malfunction. Bus OFF

Codes under Rear SAM
B214B15 - The output for switch 'Quiescent current ON' has a malfunction. There is a short circuit to positive or an open circuit.
B214B72 - The output for switch 'Quiescent current ON' has a malfunction. The actuator does not close.

I've checked for codes in this car pretty frequently in the past. I only had a code for the tumble flap related to a separate issue with the intake manifold. The list of codes above popped up recently.

I am assuming this problem is related to the dreaded CAN Bus or one of the SAM's, but would greatly appreciated any help/direction so I can pin down the fault.

 

Seeing your starter failed(high current), how old is your battery and the condition of it now to handle the starter-?
Have you disconnect the battery and reconnect-? Check codes without trying to start-?

 

The battery is high quality but I've had it for 4-5 years in the Texas heat. It's cranked the new starter just fine. I have also disconnected and reconnected the battery (a few times). I'll try checking the codes without trying to start. Also, I'm cleaning the connection at the ESP. I read this connection can cause issues.

 

Sorry for asking about battery again, I see no mention of exact voltages, if you switch on and turn headlights & mist/vog on bright, wait 20 seconds, what voltage does the battery measure while lights still on-? this will cost nothing.

 

With no load on battery: 12.00 volts ...then it bumped up to 12.04 volts

With load after 20-30 secs: 11.55 volts then it crept up to 11.66 volts.

 

It wont cost you much to confirm:
OK, when myne did that, the starter relay refused to come in one day, bought a new battery, problem solved, not saying its entirely yours. I could see my headlights also dimmed as seconds passed, battery not capable to provide power, although no load just over 12V. I would have the battery load checked to confirm or not.

My logic to this(Maybe dead wrong):
1-Battery at certain 4 year condition.
2-Starter faulty make huge draw on battery, although not blowing a fuse.
3-Battery may got a knock from this.
4-Battery now at a certain condition.
5-Repared starter connected, battery started a few times.
6-Battery now at a certain condition.
7-When tried again, starter relay not kicking in, car left with enought to power on, but no start.
8-My 1st thoughts from this the battery might now be faulty. My battery made 8 years.

Note-1:I had a relative new battery in my Mazda(1 year old), went for a meeting with it driving in mist, forgot to switch off the lights, 3 hours later dead flat... We had to jump it, drove back(70 km), used it every day, 4 days later it dropped me dead in town, new battery. That drain gave the battery a knock, which interesting only failed 4 days later.
Note-2:Another experience I had with a battery was on a Zuzuki 4cyl motorcycle. It cranked fast but did not want to start. I should have measured the voltage, well 5 day later of faultfinding, see the starter swing fast at 10.5-11V. Replaced battery problem solved, this one had me confused by listning to the starter speed.

 

Do you hear the ignition lock make a sound when it unlocks or locks?
ESL could be faulty

 

My '09 didn't start yesterday but started today. I checked the battery and it's good. It's a little over a year old and this happened before and the battery tested over 90% about a month or 2 ago. Last time I think the connection to the battery was just loose because when I tightened it, car was fine. I have a feeling something is going bad but not sure what. With all the problems i've had with this damn car, I'm considering on going back to a Honda Accord. At least I didn't have any problems in the 10 years I had it until the end.

 

Yes, I suspected the same. The ignition locks and unlocks. I replaced the brake light switch recently too. My shifter is a bit sketchy due a drink spill a long while back. I cleaned up the shifter and it works okay, but sometimes hesitates to come out of park.

 

I really appreciate your help and input. I will have the battery tested today. I still suspect the ESP or CAN BUS. I'm doing all I can to avoid taking the car to the stealer.

 

Esp wouldn't cause the car to not start.

 

My bit of experience with electronic systems are they don't like 1-water/moist/corrotion(can be seen?photographed with macro lenses if present not obviously visible with eyes---cause all sorts of complicated issues, and , 2-Varying voltages due to a not stable power supply(Battery support) or problematic AC if connected there.
Understanding your battery condition to provide claimed capcity at all times, will in any case be a worthwile experience for you.

 

Forget testing the battery. 4-5 years in the Texas heat. Replace it. Batteries have honeycomb plates of lead which degrades and falls to the bottom of the case. The more you lose the less capacity not the less voltage. Since the battery has less capacity, starting will draw the voltage down during cranking. Low voltage during cranking will run havoc with the modern electrical stuff from fuel pump to shift sensing and throw lots of codes.. Turn off the key and the battery will show full charge. Spend the bucks.

 

I had the battery tested and it checked out as okay. I may take your advice and swap it anyway. I'm still suspicious of the driver side CAN. I have another batttery handy as well. I'm gonna try this battery and see if it helps. I'm also wondering if the old starter may have damaged the system by the excess current draw it required to start.

 

It turned out the replacement starter was bad. I swapped it and the car started. I cleared all the codes. Will see if any come back. Will update you.