Circuit DescriptionThe EGR valve is controlled by a brushless motor located on top of the EGR valve. The EGR valve motor uses three different motor legs to move the valve through its range of motion. The engine control module (ECM) uses the EGR motor A, B, and C wires to command the EGR valve to the appropriate position in order to meet EGR flow targets.
The EGR valve motor contains three position sensors that detect the location of the EGR valve. These sensors report the position of the valve back to the ECM over the EGR valve position A, B, and C wires.
Component LocationThe EGR valve is located on the air intake connection.
Conditions for Running the DiagnosticsThis diagnostic runs continuously when the keyswitch is in the ON position and the engine is operating.
Conditions for Setting the Fault CodesThe ECM detects a short circuit to ground in the EGR motor supply circuits.
Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.Active and stationary regeneration of the diesel particulate filter will be disabled.The EGR valve will be closed.Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.Conditions for Clearing the Fault CodeTo validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop-and-go city driving and steady state highway driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.To validate the repair using a Chassis Dynamometer Test, utilize a routine that incorporates acceleration and motoring events, steady state highway operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.For On-Board Diagnostics (OBD) engines, the ECM will turn off the malfunction indicator lamp (MIL) after three consecutive trips where the diagnostic runs and passes.The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications
Shop TalkPossible causes of this fault code include:
One of the EGR motor circuits shorted to ground in the EGR valve motorOne of the EGR motor circuits shorted to ground in the harnessMalfunctioning ECM.
Possible Cause:1) EGR valve failure2) Engine Harness