CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 2375

  Printable Version

Overview

ISX CM871/ISM CM876 – Exhaust Gas Recirculation Temperature Sensor Circuit SMALL | MEDIUM | LARGE

Circuit Description

The exhaust gas recirculation (EGR) temperature sensor is a variable resistor sensor and is used to measure the temperature of the EGR gas flow after it exits the EGR cooler. The electronic control module (ECM) supplies 5 volts to the EGR temperature signal circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the EGR flow temperature.

The EGR temperature value is used by the ECM for the engine protection system and for engine emissions control.

Component Location

The EGR temperature sensor is located on the EGR connection tube between the EGR cooler and the air intake connection. Use the following procedure for a detailed component location view. Refer to Procedure 100-002 in Section E.

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 EGR temperature signal voltage is greater than 5.1-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 exhaust gas recirculation temperature reading is used.

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, use the following procedure to calibrate the ECM. Refer to Procedure 019-032 in Section 19.

The EGR temperature sensor shares RETURN wires in the engine harness with other sensors. An open RETURN can cause multiple fault codes to be active.

Possible causes of this fault code include:

• An open RETURN circuit in the harness, connectors or sensor.
• An open SIGNAL circuit or shorted to a voltage source.

The resistance of the EGR temperature sensor varies with the temperature. If the EGR temperature sensor is operating properly, the observed reading will be comparable to the values in the following table.

Refer to Troubleshooting Fault Code 2375.