Cummins X15 CM2450 X124B (2018 & Newer) Fault Code: 1684 PID: SPN: 3363 FMI: 4 Aftertreatment 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 tank heater control valve is located near the diesel exhaust fluid tank. Specific location will vary depending on the vehicle OEM. The tank heating coil is internal to the diesel exhaust fluid tank.

Conditions for Running the Diagnostics
This diagnostic runs continuously when diesel exhaust fluid tank heating is being commanded.

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, 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 the diagnostic runs and passes.
The ECM will turn off the amber CHECK ENGINE lamp 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
Possible causes of this fault code include:

Malfunctioning diesel exhaust fluid tank heater control valve
A short circit to ground

Possible Cause:
1) OEM harness
2) ECM calibration