Cummins ISX12 CM2250 (2010-12) Fault Code: 3237 PID: SID 254 SPN: 4340 FMI: 3 Aftertreatment Diesel Exhaust Fluid Line Heater 1 Circuit- Voltage Above Normal or Shorted to High Source

Circuit Description
The aftertreatment diesel exhaust fluid line heater 1 is controlled by the aftertreatment diesel exhaust fluid controller, and receives power through the switch side of the diesel exhaust fluid line heater relay.

Component Location
The aftertreatment diesel exhaust fluid line heater 1 is located on the supply line between the diesel exhaust fluid dosing unit and diesel exhaust fluid dosing valve.

Conditions for Running the Diagnostics
This diagnostic runs when the keyswitch is in the ON position and the heater is commanded ON.

Conditions for Setting the Fault Codes
The aftertreatment diesel exhaust fluid controller detects that the line heater voltage is above a calibratible value.

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.
The line heater will be disabled.
Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
Conditions for Clearing the Fault Code
To validate the repair, perform a key cycle, and then use INSITE? electronic service tool to perform the Diesel Exhaust Fluid Doser System Heater Test found under ECM Diagnostic Tests.
The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after all three line heaters are commanded on and the diagnostic runs and passes.
The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
For On-Board Diagnostic (OBD) engines, the ECM will turn off the 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
Possible causes of this fault include:

Malfunctioning line heater
Short circuit to battery in the aftertreatment diesel exhaust fluid controller harness
Malfunctioning aftertreatment diesel exhaust fluid controller.
Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

Possible Cause:
1) Aftertreatment DEF line heater 1 failure
2) Aftertreatment DEF controller failure
3) ECM calibration