PACCAR PX-9 CM2350 (2013-17) Fault Code:1977 PID:SID 382 SPN:3556 FMI:5 Aftertreatment Doser Circuit – Current Below Normal or Open Circuit.

Reason:
Aftertreatment Doser Circuit – Current Below Normal or Open Circuit. High resistance, short circuit, or open circuit detected on the aftertreatment fuel injector circuit.

Effect:
Possible reduced engine performance.

Circuit Description:
The aftertreatment fuel injector is electronically controlled by the engine electronic control module (ECM) through a pulse width modulated (PWM) signal. The amount of fuel injected is determined by how long the PWM signal to the injector is on.

Component Location:
The aftertreatment fuel injector is installed in the exhaust system in the turbocharger adapter pipe. The aftertreatment fuel pressure sensor and aftertreatment fuel shutoff valve are installed in the shutoff valve manifold.

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 a circuit error within the aftertreatment fuel injector circuit.

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) Active regeneration of the aftertreatment diesel particulate filter will be disabled unitl the next key cycle.
3) 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, start the engine and perform the INSITE™ electronic service tool Aftertreatment Diesel Particulate Filter Regeneration Test.
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:
Possible causes of this fault code include:
1) An open circuit in the supply or return wire in the engine harness
2) An open circuit in the aftertreatment fuel injector solenoid
3) A short circuit to ground in the engine harness
4) A short circuit to voltage source in the engine harness
5) High resistance in the aftertreatment fuel injector solenoid
6) An extremely low resistance in the aftertreatment fuel injector solenoid
7) A damaged ECM