CM870 and ISX Engines – FAULT CODE 598

Battery Voltage Monitor – Very Low Voltage

Overview

CODE	REASON	EFFECT
Fault Code: 598 PID: P167 SPN: 167 FMI: 1/1 LAMP: Red SRT:	Electrical Charging System Voltage Low – critical level. Very low battery voltage detected by the battery voltage monitor feature.	Red lamp illuminated until very 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.

Battery Voltage Monitor Circuit SMALL | MEDIUM | LARGE

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 OEM 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 manual for the battery location.

Shop Talk

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

Possible causes of this fault code:

• Undercharged batteries caused by a faulty alternator or regulator.

Refer to Troubleshooting Fault Code t05-598