PACCAR PX-9 CM2350 (2013-17) Fault Code:3422 PID: SPN:4344 FMI:3 Aftertreatment Diesel Exhaust Fluid Line Heater 3 Circuit – Voltage Above Normal or Shorted to High Source

Reason:
Aftertreatment Diesel Exhaust Fluid Line Heater 3 Circuit – Voltage Above Normal or Shorted to High Source. High signal voltage detected at the diesel exhaust fluid line heater 3 circuit.

Effect:
Possible reduced engine performance.

Circuit Description:
The aftertreatment diesel exhaust fluid line heaters are used to defrost and/or prevent freezing of the diesel exhaust fluid lines.

Component Location:
The aftertreatment diesel exhaust fluid line heater 3 is located on the suction line between the diesel exhaust fluid tank and diesel exhaust fluid dosing unit.

Conditions for Running the Diagnostics:
This diagnostic runs when the keyswitch is in the ON position and line heating is commanded OFF.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the line heater voltage was above a calibratible value and the line heater current was above a calibratible value.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
2) The line heater will be disabled.
3) Diesel exhaust fluid injection into the aftertreatment system is disabled.
4) 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:
1) 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.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) 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.
5) 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:
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 Causes:
1) Malfunctioning line heater
2) Malfunctioning aftertreatment diesel exhaust fluid contoller.
3) A short circuit to battery in the OEM harness