CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 1879

Aftertreatment Particulate Filter Differential Pressure Sensor Circuit – Voltage Above Normal, or Shorted to High Source


Overview

CODE REASON EFFECT
Fault Code: 1879
PID: S324
SPN: 3251
FMI: 3/3
LAMP: Amber
SRT: 

Aftertreatment Particulate Filter Differential Pressure Sensor Circuit – Voltage Above Normal, or Shorted to High Source. High signal voltage detected at the aftertreatment differential pressure sensor circuit.

Active aftertreatment diesel particulate filter regeneration will be disabled.

ISX and ISM Aftertreatment Diesel Particulate Filter Differential Pressure Sensor
SMALL | MEDIUM | LARGE

Circuit Description

The electronic control module (ECM) provides a 5 volt supply to the aftertreatment diesel particulate filter differential pressure sensor on the sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The aftertreatment diesel particulate filter differential pressure sensor provides a signal to the ECM on the aftertreatment diesel particulate filter differential pressure sensor signal circuit. This sensor signal voltage changes based on the differential pressure across the aftertreatment diesel particulate filter.

Component Location

The aftertreatment diesel particulate filter differential pressure sensor is located in the aftertreatment system. Refer to the OEM troubleshooting and repair manual for exact location of the aftertreatment system.

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 aftertreatment diesel particulate filter differential pressure signal voltage is greater than 4.75-VDC for more than 1 second.

Action Taken When the Fault Code is Active

  • The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
  • A default value for the aftertreatment diesel particulate filter differential pressure is used.
  • Active aftertreatment diesel particulate filter regeneration will be disabled.

Conditions for Clearing the Fault Code

The ECM will turn off the amber CHECK ENGINE light immediately after 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.

Possible causes of this fault code include:

  • Open return circuit in the harness, connectors, or sensor.
  • Signal circuit shorted to sensor supply or battery voltage.

Refer to Troubleshooting Fault Code t05-1879

Last Modified:  09-Jul-2010