Sprinter network/ecm fault
This is an interesting one that a few of us have been fighting with. This 2007 Dodge Sprinter 3500 Diesel motorhome was towed in with a no start complaint. I observed and confirmed the no start, along with no ECM communications. One thing worth noting, cycling the key, occasionally the vehicle would crank for half a second to a second, however it happened to fast to determine if the ecm was talking.
Powers and grounds have all been verified, however in the process of verifying power to C2 P41@ecm, the starter jumped with C2 disconnected. I was unable to duplicate this. P42 is the ASD Relay enable command, P44 is starter so I find it extremely unlikely that I bridged the connection to the starter relay enable circuit with the probe.
We removed the ECM, and built a harness to supply power and ground on the bench to attempt to communicate via the can c bus as well as pin 3 and 7 on the DLC, however there are some wiring discrepencies with regards to what is what. One diagram shows p18 and p43 as direct bus lines to the ECM, one shows just pin 18. We attempted to communicate both with and without a terminating resistor added inline to bring us from 120ohm to 60ohm. Exact wiring was:
Fused power to C2 p1, p3, p5, p41 Ground to C2 P2, p4, p6 Can Hi to P51 Can low to P52 K line to pin 18
Regardless we were unable to attain comms with the ecm. Based upon the initial symptoms prior to diving in, I was looking very closely at the ignition switch, as that is the CGW, but moreso because of the intermittent nature of the starter operation, however when monitored via scan tool, the start command is being given when the key is in the start position.
Code lists are attached, we have been unable to recreate the miscgw codes, which both defined as MIS internal fault, however all of the comms codes related to ECM being on-comms have reset immediately. Based upon the trouble tree based on no ECM comms, we have verified integrity of all comms lines between the CGW and ECM, as well as verified the diagnostic junction block integrity, and the network is up as we are communiating.
We are pretty confident we have a failed ECM, we are questioning the ignition switch integrity at this point.
Hi Eric, Most of the codes are in relation to modules loosing communications with the CDI controller. Although there are many low voltage codes the vehicle is a no start so it is likely these codes were set due to long cranking times lowering system voltage. If the buss was down I would expect non communication with multiple modules therefore I believe your assessment of a failed CDI controller…
I had one of these a few weeks ago. It was part of a fleet and there was a GPS connected. Before condemning the ECU I had them try driving without the GPS. It was the GPS causing the issue.
Where/how was the GPS connected if you don't mind me asking?
GPS was mounted near Engine ECU and spliced into the CAN network wires. (Above Brake and Accelerator Pedals) If it has GPS, you will see wiring that does not look factory installed under the dash.
Not familiar with the bidirectional controls on the MB Sprinters and I did not look at a schematic for this vehicle. If you are questioning the ignition switch can you bypass it by either using bidirectional controls or manually?