CAT 3406E (Prefix 5DS or 1LW) Fault Code: 51 PID: 168 SPN: FMI: 2 ECM Battery Power Intermittent

This condition indicates that the battery circuit to the Engine Control Module (ECM) has a battery condition that is intermittent while the engine is running. If battery voltage disappears without returning, the ECM will not log this diagnostic code and the engine will shut down.

The ECM detects the following conditions:

•The ignition key switch is in the ON position.
•The engine is running.
•The engine is not cranking.
•The ECM has been powered for at least three seconds.

The ECM will detect one of the following conditions:

•The battery voltage drops below 6 VDC for at least 0.50 seconds.
•Three voltage readings in the past seven seconds were below 6 VDC.

Probable Causes:

1) ECM Connection/harness
2) Battery voltage at ECM
3) Truck battery or battery cable issue
4) Aftermarket engine protection switch
5) ECM Failure