Cummins ISB CM850 (2003-06) Fault Code: 585 PID: SID 39 SPN: 677 FMI: 4 Starter Relay Circuit – Voltage Below Normal or Shorted to Low Source. Low voltage detected at starter lockout circuit.

The ECM monitors the voltage level on this circuit. If it detects a low voltage when the signal is commanded on, it records this fault code. This fault code can be caused by a short circuit to ground in the starter lockout relay, OEM harness, or connectors.

Possible repairs:

1)Replace the starter lockout relay.
2)Repair or replace the OEM harness.
3)The removal and installation of the connector may correct the fault.
4)Replace the ECM.