CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 1893

  Printable Version

Overview

ISX – EGR Valve Circuit SMALL | MEDIUM | LARGE

ISM – EGR Valve Circuit SMALL | MEDIUM | LARGE

Circuit Description

The exhaust gas recirculation (EGR) valve is a smart device and receives commands from the engine electronic control module (ECM) via the SAE J1939 data link. The EGR valve performs its own internal diagnostics and reports failures back to the primary engine ECM using the SAE J1939 data link.

The EGR valve is opened by a motor located on top of the EGR valve. A pin is extended from the motor and contacts the dual-poppet valve to open the EGR valve. A spring is used to close the EGR valve.

Component Location

The EGR valve location can vary depending on the engine application. 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 or when the engine is running.

Conditions for Setting the Fault Codes

The primary engine ECM does not receive a valid SAE J1939 message from the EGR valve for more than 5 seconds.

Action Taken When the Fault Code is Active

• The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
• The EGR valve will be closed.

Conditions for Clearing the Fault Code

The ECM will turn off the amber CHECK ENGINE light and enable the EGR valve operation immediately after a valid SAE J1939 message is received from the EGR valve.

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, calibrate the ECM. For ISX and ISM engines, see the following procedure in the corresponding Troubleshooting and Repair Manual for the engine being serviced. Refer to Procedure 019-032 in Section 19.

This fault code is logged when the primary engine ECM did not receive valid SAE J1939 information from the EGR valve.

Possible causes of this fault code include:

• The EGR valve is not receiving power from the ECM. This could be caused by an open circuit in the power supply wire or low voltage supplied by the primary engine ECM.
• Open return circuit on the EGR valve circuit between the engine ECM and the EGR valve.
• Open or short circuit on the SAE J1939 data link circuit between the ECM and the EGR valve.
• Intermittent communications between the EGR valve and the primary engine ECM on the SAE J1939 data link.
• Malfunctioning termination resistors in the engine data link harness.
• A malfunctioning engine ECM.
• A malfunctioning EGR valve.

Refer to Troubleshooting Fault Code t05-1893