Cummins X15 CM2450 X124B (2018 & Newer) Fault Code: 4951 PID: SPN: 6655 FMI: 3 Maintain ECU Power Lamp Circuit- Voltage Above Normal or Shorted to High Source

Circuit Description
The Engine Control Module (ECM) requires battery power when the keyswitch is ON and for a period of time after the keyswitch is turned OFF. The battery power required lamp is an optional lamp that can be installed to indicate when it is acceptable to remove battery power from the ECM. The lamp will be illuminated when the ECM requires battery power and will extinguish once it is acceptable to remove battery power.

Component Location
The battery power required lamp is an OEM installed component. Refer to the OEM for component location.

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
The Engine Control Module (ECM) detected the battery power required lamp signal circuit was out of range high.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
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 amber CHECK ENGINE lamp immediately after 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
Possible causes of this fault code include:

A pin-to-pin short circuit
An open circuit in the OEM harness
A malfunctioning battery power required lamp

Possible Cause:
1) ECU power lamp failure
2) OEM harness
3) Engine harness
4) ECM calibration