CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 597

Electrical Charging System Voltage – Data Valid but Below Normal Operational Range – Moderately Severe Level


Fault Code: 597
PID: P167
SPN: 167
FMI: 1/18
LAMP: Amber

Electrical Charging System Voltage – Data Valid but Below Normal Operational Range – Moderately Severe Level. Low battery voltage detected by the battery voltage monitor feature.

Amber lamp will light until low battery voltage condition is corrected.

ISX and ISM – ECM Power Supply Circuit

Circuit Description

The electronic control module (ECM) receives constant voltage from the batteries through the unswitched battery wires that are connected directly to the positive (+) battery post. The ECM receives switched battery input through the vehicle keyswitch wire when the vehicle keyswitch is turned on.

Component Location

The ECM is connected to the battery by the ECM power harness. This direct link provides a constant power supply for the ECM. The location of the battery will vary with the OEM. Refer to the OEM troubleshooting and repair manual for the battery location.

Conditions for Running the Diagnostics

This diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes

The ECM detects that the battery voltage is less than 10 VDC.

Action Taken When the Fault Code is Active

  • The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code

The ECM will turn off the amber CHECK ENGINE light when the diagnostic runs and passes.

Shop Talk

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, recalibrate the ECM. Refer to Procedure 019-032 (ECM Calibration Code) in Section 19 in the corresponding Troubleshooting and Repair Manual for the engine being serviced.

This fault code is part of the Battery Voltage Monitor feature. The ECM can increase idle speed and deactivate idle decrement switch if Idle Speedup is enabled. View the Battery Voltage Monitor feature settings using the INSITE™ electronic service tool. Disabling the Battery Voltage Monitor feature will also disable this fault code.

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

Possible causes of this fault:

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

Refer to Troubleshooting Fault Code t05-597

Last Modified:  09-Jul-2010