Circuit DescriptionThe variable geometry turbocharger (VGT) is electronically activated by the VGT actuator. The VGT actuator is a smart device that receives information via the J1939 data link from the primary engine electronic control module (ECM). The VGT actuator performs its own diagnostics and reports malfunctions back to the primary engine ECM, using the J1939 data link.
Component LocationThe VGT actuator is located on the turbocharger bearing housing.
Conditions for Running the DiagnosticsThis diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.
Conditions for Setting the Fault CodesThe primary engine ECM does not receive a valid J1939 message from the VGT actuator for more than 1 second.
Action Taken When the Fault Code is ActiveThe ECM illuminates the red STOP ENGINE lamp and/or Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.The VGT will move to the default open position.Conditions for Clearing the Fault CodeTo validate the repair, start the engine and let it idle for 1 minuteThe 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 after the diagnostic runs and passes.For OBD engines, the ECM will turn off the MIL after three consecutive trips where the diagnostic runs and passesThe ?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 TalkTroubleshoot high inactive counts of Fault Code 2636 as an active fault code.
Possible causes of this fault code include:
The VGT actuator is not receiving power from the ECM. This can be caused by an open circuit in the power supply wire or low voltage supplied by the primary engine ECM.Rapid cycling of the keyswitchAn open return circuit on the VGT actuator circuitAn open or short circuit on the J1939 data link circuit between the ECM and VGT actuatorIntermittent communications between the VGT actuator and the primary engine ECM on the J1939 data linkA damaged termination resistor in the engine data link harnessA malfunctioning engine ECM.
Possible Cause:1) OEM wiring harness2) Intake NOx sensor failure3) VGT Actuator failure4) Engine wiring harness5) OEM terminating resistor failure6) ECM calibration