CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 2351

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Overview

ISX – EGR Valve Control Circuit SMALL | MEDIUM | LARGE

ISM – EGR Valve Control 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 J1939 datalink. The EGR valve performs its own internal diagnostics and reports failures back to the primary engine ECM using the J1939 datalink.

The EGR valve is opened by a motor located on top of the EGR valve. A motor shaft extends from the motor and contacts the dual-poppet valve to open the EGR valve. The EGR valve motor does not actually retract the EGR valve. The motor current is reduced and the spring pushes the EGR valve closed.

Component Location

The EGR valve location can vary depending on the engine application. Refer to Procedure 100-002 (Engine Diagrams) in Section E for a detailed component location view.

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 EGR valve has detected an internal error in the EGR valve smart device.

Action Taken When the Fault Code is Active

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

Conditions for Clearing the Fault Code

The diagnostic will clear at initial key-on if the failure condition no longer exists. The ECM will turn off the amber CHECK ENGINE light and enable EGR valve operation 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.

This fault code is logged when the EGR valve has detected an internal error. All failure modes listed below are internal to the EGR valve.

Possible causes of this fault code include:

• Motor terminal short to ground internal to the EGR valve.
• Motor terminal short to battery internal to the EGR valve.

Refer to Troubleshooting Fault Code t05-2351