Circuit DescriptionThe aftertreatment diesel exhaust fluid dosing unit performs many functions, one of which is to generate adequate diesel exhaust fluid pressure in the lines, using a pump, to allow for dosing. The ECM provides a battery voltage supply and a ground to the diesel exhaust fluid dosing unit. The ECM also supplies a signal to the dosing unit to control the diesel exhaust fluid output. This signal changes, based on the diesel exhaust fluid pressure being commanded.

Component LocationThe aftertreatment diesel exhaust fluid dosing unit location is original equipment manufacturer (OEM) dependent. Refer to the OEM service manual.

Conditions for Running the DiagnosticsThis diagnostic runs when the diesel exhaust fluid dosing unit is in the priming or dosing state.

Conditions for Setting the Fault CodesThe Engine Control Module (ECM) detected the aftertreatment diesel exhaust fluid dosing unit signal voltage was greater than a calibratible value or the diesel exhaust fluid dosing unit supply was shorted to battery or open circuit.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.Diesel exhaust fluid injection into the aftertreatment system is 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 CodeTo validate the repair, perform the “Aftertreatment Diesel Exhaust Fluid System Leak Test” found under “ECM Diagnostic Tests” in the INSITE™ electronic service toolThe 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 TalkPossible causes of this fault code include:

Short to battery voltage in the diesel exhaust fluid dosing unitA short circuit to battery in the OEM harnessReference 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) OEM harness2) Aftertreatment DEF dosing unit failure3) ECM calibration