Circuit DescriptionThe variable geometry turbocharger (VGT) is electronically activated by the VGT actuator. The VGT actuator is a smart device and receives information via the J1939 data link from the primary engine control module (ECM). The VGT actuator performs its own diagnostics and reports malfunctions back to the primary engine ECM, using the J1939 data link. The ECM then decodes the error message and converts it to a fault code.

Component LocationThe VGT actuator is located on the turbocharger bearing housing.

Conditions for Running the DiagnosticsThis diagnostic runs when the keyswitch is initially turned to the ON position.

The keyswitch must be turned OFF for more than 30 seconds before this diagnostic will run at initial key ON.

Conditions for Setting the Fault CodesThe Variable Geometry Turbocharger (VGT) actuator position was not known during initial power ON.

Action Taken When the Fault Code is ActiveThe ECM illuminates the red STOP ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.

VGT actuation will be disabled.Exhaust Gas Recirculation (EGR) valve operation will be disabled.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, perform a key cycle, and leave the keyswitch in the ON position for 1 minute. Note that the keyswitch must be completely turned OFF for more than 30 seconds before this diagnostic will run at initial key ON.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 red STOP ENGINE lamp immediately after the diagnostic runs and passes.For On-Board Diagnostics (OBD) engines, the ECM will extinguish 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 TalkThis fault code can only be logged after the VGT actuator has been removed or replaced, and then not installed correctly. The gear alignment between the actuator and the turbocharger housing is misaligned. The correct installation procedure must be followed when replacing the VGT actuator.

Possible Cause:1) Turbocharger failure2) VGT Actuator failure3) ECM calibration