Cummins ISX15 CM2250 (2010-12) Fault Code: 3734 PID: 102 SPN: 862 FMI: 4 Crankcase Breather Filter Heater Circuit- Voltage Below Normal or Shorted to Low Source

Circuit Description
The crankcase breather heater is used to keep the crankcase breather filter housing from freezing. The engine control module (ECM) supplies 12-VDC to the breather heater when heating is commanded.

Component Location
The crankcase breather heater is mounted to the crankcase breather filter 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
The ECM detects that the crankcase breather heater signal circuit is shorted to ground.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
The crank case breather heater will be disabled.
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 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.

Shop Talk
Possible causes of this fault code include:

Malfunctioning ECM.
Open Crankcase Breather Heater Circuit

Possible Cause:
1) Crankcase breather heater failure
2) Engine harness
3) ECM failure