Cummins ISB4.5 CM2150 Fault Code: 1684 PID: 202B 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 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 the keyswitch is in the ON position.

Conditions for Setting the Fault Codes
The diesel exhaust fluid controller has detected low supply voltage or a short circuit 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.

Conditions for Clearing the Fault Code
-To validate the repair, start the engine and let it idle for 1 minute.
-The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.
-The ECM will turn off the MIL after 3 consecutive ignition cycles that the diagnostic runs and passes.
-This fault code and MIL can also be cleared with INSITE™ electronic service tool.

Shop Talk
The diesel exhaust fluid tank heater control valve may be powered by an OEM suppied 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
-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.