Cummins ISB CM550 (1990-94) Fault Code: 111 PID: SID 254 SPN: 629 FMI: 12 Engine Control Module – critical internal failure. Error internal to the ECM related to memory hardware failures or internal ECM voltage supply circuits.

This fault code can only be caused by an internal ECM problem. Repairs are not possible for the ECM.

Possible repairs:

1)Replace the ECM.

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