Hello. I joined the site back in 2012 when I had my 2000 ML430, but it was involved in a freak accident 3 years later and I got rid of it.

I've recently acquired a 2012 C300 that now will sometimes crank, but doesn't start, while other times will start, runs for about 5-10 seconds, then just dies. When it runs, if I try to give it gas, it also dies immediately.

The diagnostic codes are:
- P0521 (The charge movement flap [cylinder bank 1] is faulty: current and stored)
- P1304 (The pressure sensor/pressure switch of the evaporative emission [EVAP] control system is faulty: stored)
- P1088 (A great leakage in the evaporative emission (EVAP) control system was identified: current and stored)
- P1437 (Communication with the A/C is faulty: current and stored [event])
- P0866 (The on-board power supply voltage is too low (current and stored)
- P1106 (The power supply at the input of the combustion ECM is faulty: current and stored)
- P2225 (The left fuel level sensor has a short circuit to battery [+]: stored)

Because it ran and died for a short while at times, I first took off the intake and the MAF sensor (but left it plugged in) and pushed some starter fluid directly into the throttle body while someone was cranking the car. The car started and ran for about 3 seconds, then died. That test confirmed for me that it is more likely a fuel issue, so I stayed the course.

Next, I used my scan tool to re-verify that I was getting pressure at the rail and I was getting over 4 bars. To be absolutely sure, I went and rented a pressure tester from AutoZone and static pressure read around 38 psi with key in the position just before cranking. Once I cranked the vehicle, the pressure went as high as 58 psi while the car ran again for about 3 seconds before it died. The pressure then dropped to around 55 psi.

Next, I got a Noid light, unplugged one of the fuel injector connectors and plugged it into the connector. Upon cranking, I did see the Noid light blink/flash. I was able to get to another fuel injector connector easily, so I repeated the test on the same bank and the Noid light again blinked/flashed. So, it seems I am getting signal from the ECM to fire the fuel injector, but I wanted to see whether fuel was actually getting into the cylinder.

Since I was doing all that cranking, I grabbed my borescope and lowered the camera into one of the combustion chambers after removing the spark plug to see whether there was any evidence of fuel in the chamber. It was completely dry. I checked the spark plug and it was also dry with no smell of fresh fuel. I pulled at least 4 spark plugs and checked for gasoline and they were all dry. I tried one last thing: I tucked a piece of paper down into one of the spark plug holes, while putting the other spark plugs back in, I put the ignition coil back into that one cylinder without the spark plug, then had the car cranked again, but no fuel could be found or smelled on the paper.

So, fuel is being blocked from entering the chamber somehow. It seems unlikely that a number of fuel injectors are completely clogged causing no fuel to enter the combustion chamber, although that could be the case. It sounds more like a control issue to me. I did check all 6 fuses related to the fuel system as well as the relay and they all work fine. I've also energized the fuel pump by putting 12 volts to it and it runs. It also ran when I commanded it to do so with the scan tool. I wanted to test the Fuel Pump Control Module or FSCU, but didn't have a wiring diagram. If someone can send one along, I'd greatly appreciate it.

I'm also starting to think that the P1106 (The power supply at the input of the combustion ECM is faulty: current and stored) might be playing a role in this somehow, but I'm not sure how to go about diagnosing this fault. Would anyone have a pinout of the ECM for a 2012 C300? I want to move towards testing for powers and grounds at the ECM connector.

Am I moving in the right direction in terms of my diagnosis?

Thank you so much in advance for any assistance you can give.

 

Update:There is no power on pin #3 at the ECM connecter with ECM unplugged and vehicle on, although there is power at fuse 25 and relay on the front SAM, when ECM is plugged in. Also, there is no power on pin 94 and 95, which is powered by fuse 24, but fuse is okay. I tested the circuit at the SAM and I do have good ground and both powers there. I've also tested the three grounds on pins 2, 4, and 6 at the ECM, and they all tested good.

Are there other tests I should consider doing before condemning the ECM?