Cummins ISX12 CM2250 (2010-12) Fault Code: 1977 PID: SID 382 SPN: 3556 FMI: 5 Aftertreatment Doser Circuit- Current Below Normal or open Circuit

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 outlet flange.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is turned ON.

Conditions for Setting the Fault Codes
The ECM detects a circuit error within the aftertreatment fuel injector 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.
Active regeneration of the aftertreatment diesel particulate filter will be disabled until the next key cycle.
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 INSITE? electronic service tool Aftertreatment Diesel Particulate Filter Regeneration Test. Once the temperatures in the aftertreatment are warm enough to inject diesel fuel into the exhaust, the diagnostic will run.
The fault code status displayed by the 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 after the diagnostic runs and passes.
For On Board Diagnostic (OBD) engines, the ECM will turn off the MIL after 3 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:

An open circuit in the supply or return wire in the engine harness
An open circuit in the aftertreatment fuel injector solenoid
A short circuit to ground in the engine harness
A short circuit to voltage source in the engine harness
High resistance in the aftertreatment fuel injector solenoid
An extremely low resistance in the aftertreatment fuel injector solenoid
A damaged ECM.

Possible Cause:
1) Aftertreatment Fuel Injector failure
2) Wiring Harness failure
3) Engine harness failure
4) ECM failure