Cummins ISX CM870 (2003-06) Fault Code: 2385 PID: S027 SPN: 641 FMI: 3 Variable geometry turbocharger actuator driver circuit – voltage above normal or shorted to high source. Open circuit or high voltage detected at turbocharger control valve circuit.

Possible causes:

1)Open circuit in the engine harness or connectors
2)Open circuit in the turbocharger control valve
3)Signal circuit short to voltage source in the engine harness
4)Loose ground connection through the engine wiring harness to the engine block ground terminal. Engine test experience has proven that a loose nut on the engine block stud which results in a poor ground connection at the engine harness ring terminal will cause intermittent Fault Code 2385.

Possible repairs:

1)Replace the turbocharger control valve.
2)Replace the ECM.
3)Repair or replace the engine harness.