CM870 and ISX Engines – FAULT CODE 597

Voltage Monitor – Low Voltage


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

Electrical Charging System Voltage Low – Warning Level. Low battery voltage detected by the battery voltage monitor feature.

Amber lamp will light until low battery voltage condition is corrected. The electronic control module (ECM) can increase idle speed and deactivate idle decrement switch if idle speedup is enabled.

Voltage Monitor 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.

Shop Talk

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 refrigerators, citizens band radio amplifiers, numerous exterior lights, or other accessories.

Refer to Troubleshooting Fault Code t05-597

Last Modified:  01-Sep-2010