Cummins X15 CM2450 X124B (2018 & Newer) Fault Code: 1938 PID: SID 212 SPN: 3597 FMI: 18 ECU Power Output Supply Voltage 1- Data Valid But Below Normal Operational Range- Moderately Severe Level

Circuit Description
The 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 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
Voltage supplied to the Variable Geometry Turbocharger (VGT) actuator dropped below 10-VDC for 10 seconds and the engine speed was at zero rpm or greater than 575 rpm.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
Conditions for Clearing the Fault Code
To validate the repair, perform a key cycle, 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 amber CHECK 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 Talk
This fault code is logged when the voltage to the VGT actuator drops below 10-VDC. The VGT will still continue to respond to commands from the primary engine ECM.

Possible Cause:
1) Battery Failure
2) ECM failure