Cummins ISB4.5 CM2150 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 ECM. The VGT actuator performs its own diagnostics and reports errors back to the primary engine ECM using the J1939 datalink.

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.

Conditions for Clearing the Fault Code
-To validate the repair, perform a key cycle. The diagnostic will clear at initial key-ON if the error condition no longer exists.
-The ECM will turn off the red STOP ENGINE lamp and enable VGT operation immediately after the diagnostic runs and passes.
-The ECM will turn off the MIL after 3 consecutive ignition cycles that the diagnostic runs and passes.
-This fault code and MIL can also be cleared with INSITE™ electronic service tool.

Shop Talk
This fault code is logged when the ECM has detected that an incorrect VGT actuator has been installed on the turbocharger.