Detroit DD15 GHG14 (2014-16) Fault Code: SPN 677 FMI 2 (MCM, CPC) Low or No Voltage for the Starter Switch

NOTE: Please see the step by step troubleshooting procedures for this specific code.

1. If 677-2 inactive, clear the code, start the engine, and if it doesn’t come back release the vehicle.
2. Wiring on the MCM 21-pin connector between pin 20 and ground. Should have 11.5 or more volts.
3. Wiring on the CPC connector #1 between pin 18 and ground. If less than 11.5 Volts, repair wiring.