Cummins ISC CM2150 (2007-09) Fault Code: 596 PID: 167 SPN: 167 FMI: 0 Electrical Charging System Voltage – Data Valid But Above Normal Operating Range – Moderately Severe Level. High battery voltage detected by the battery voltage monitor feature.

Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, calibrate the ECM.

This fault code is part of the Alternator Failure Warning feature. The ECM can increase idle speed and deactivate the idle decrement switch if idle speedup is enabled. View the Alternator Failure Warning feature settings with INSITE™ electronic service tool. Disabling the Alternator Failure Warning feature will also disable this fault code.

Make sure the ECM battery supply (+) is coming directly from the battery and not the starter.

Possible causes:

1)Overcharged batteries caused by a malfunctioning alternator or regulator.

Possible repairs:

1)Tighten the battery connections and clean the battery terminals.
2)Charge or replace the battery.
3)Repair or replace the alternator, regulator, and/or OEM wiring to the alternator.