Cummins ISM CM875 (2003-06) Fault Code: 597 PID: P167 SPN: 167 FMI: 1/18 Electrical Charging System Voltage – Data Valid But Below Normal Operating Range – Moderately Severe Level. Low battery voltage detected by the battery voltage monitor feature.

Make sure the ECM unswitched battery supply is coming directly from the battery and not the starter.

Possible causes:

1)Undercharged batteries caused by a malfunctioning alternator or regulator.
2)High-current devices on the vehicle such as citizens band radio amplifiers, numerous exterior lights, or other accessories.

Possible repairs:

1)Charge or replace the battery.
2)Repair or replace the alternator and/or OEM wiring to the alternator.
3)Repair or replace the battery harness.
4)Repair or replace the OEM power harness.