Cummins ISX12 CM2250 (2010-12) Fault Code: 2635 PID: SPN: 641 FMI: 31 VGT Actuator Driver Circuit- Condition Exists

Circuit Description
The 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 errors back to the primary engine ECM using the J1939 data link.

Component Location
The VGT actuator is located on the turbocharger bearing housing.

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
This fault code can be activated for the following reasons:

The ECM has detected a calibration incompatibility between the VGT actuator and the ECM calibration.
The VGT actuator has detected that the system voltage is incorrect for the installed VGT actuator part number.
The ECM has detected an incorrect VGT actuator installed on the turbocharger.
Action Taken When the Fault Code is Active
The ECM illuminates the red STOP ENGINE lamp and/or Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
VGT actuation will be disabled.
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 Code
To validate the repair, start the engine and let it idle for 1 minute.
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 after the diagnostic runs and passes.
For On-Board Diagnostic (OBD) engines, the ECM will turn off the 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 Talk
This fault code is logged when the ECM has detected that an incorrect VGT actuator has been installed on the turbocharger.

Possible Cause:
1) ECM calibration