Electronic Control System Signature, ISX and QSX15 Engines – FAULT CODE 596

Voltage Monitor – High Voltage


Fault Code: 596
PID: P167
SPN: 167
FMI: 0/16
LAMP: Yellow

High battery voltage detected by the battery voltage monitor feature.

Yellow lamp will be lit until high battery voltage condition is corrected.

Voltage Monitor Supply Circuit

Circuit Description

The electronic control module (ECM) receives unswitched battery input through the OEM harness. There are two in-line 15-amp fuses in the unswitched battery wire of the OEM harness to protect the engine harness from overheating. The battery return wires are connected directly to the negative (-) battery post.

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. Use 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 code:

  • Overcharged batteries caused by a faulty alternator or regulator.

Refer to Troubleshooting Fault Code t05-596.

Last Modified:  26-Oct-2010