CAT 3126B Fault Code: 168-00 PID: Flash Code 51 SPN: 168 FMI: 0 Excessive ECM Battery Power

This condition indicates that the battery circuit to the Engine Control Module (ECM) has excessive voltage while the engine is running.

The ECM detects the following conditions:

•For 12 V systems, the battery voltage to the ECM exceeds 16 V for more than 0.5 seconds.
•For 24 V systems, the battery voltage to the ECM exceeds 32 V for more than 0.5 seconds.

The ECM also detects the following conditions:

•The engine control is in the ON mode.
•The engine is not cranking.
•The engine is running.
•The ECM has been powered for at least three seconds

Probable Causes:

1) Aftermarket device preventing battery voltage from getting to ECM
2) Problem with wiring between ECM and battery
3) Low voltage battery or failed charging system
4) Keyswitch issue or wiring from keyswitch to ECM or battery
5) ECM Failure