Cummins ISX12 CM2250 (2010-12) Fault Code: 1684 PID: SPN: 3363 FMI: 4 Aftertreatment 1 Diesel Exhaust Fluid Tank Heater- Voltage Below Normal or Shorted to Low Source

Circuit Description
The aftertreatment diesel exhaust fluid tank heater keeps the diesel exhaust fluid from freezing in the diesel exhaust fluid tank. The tank heater consists of an electrically powered tank heater control valve which controls the flow of engine coolant to a heating coil inside the diesel exhaust fluid tank. The tank heater control valve opens to allow coolant to flow to the heating coil when heating is commanded, and closes when heating is no longer required.

Component Location
The diesel exhaust fluid (DEF) tank heater control valve is installed on the coolant supply line located near the DEF tank. Specific locations will vary depending on the OEM.

The diesel exhaust fluid (DEF) tank heating coil is internal to the DEF tank.

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 low signal voltage or a short to ground at the diesel exhaust fluid tank heater circuit.

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.
Diesel exhaust fluid tank heating 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, 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 light immediately after the diagnostic runs and passes.
For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (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
The diesel exhaust fluid tank heater control valve may be powered by an OEM supplied power relay, which is connected to the aftertreatment diesel exhaust fluid controller harness. When troubleshooting wiring harness issues, it may be necessary to include the optional line heater relay.

Possible causes of this fault code include:

Short to ground in the aftertreatment diesel exhaust fluid controller harness
Malfunctioning diesel exhaust fluid tank heater control valve
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 controller failure
2) ECM calibration