Cummins ISX11.9 code 1977 is the diagnostic fault code for the aftertreatment doser circuit with current below normal or open circuit, and this page describes the official Cummins troubleshooting document for it. This fault is reported as SPN 3556 / FMI 5, and PID S382. The 15-page PDF gives the circuit description, the conditions that set fault code 1977, the action taken when it is active, and the guided troubleshooting steps needed to confirm and repair it.
Official document details
| Brand | Cummins |
|---|---|
| Model coverage | ISX11.9 CM2250 (2010-12), ISX12 CM2250 (2010-12) |
| System / Group | DTCs — Fault Code 1977 |
| SPN / FMI | 3556 / 5 |
| PID | S382 |
| Warning lamp | Amber |
| Pages | 15 |
| File size | 0.3 MB |
| Format | |
| Language | English |
Document table of contents
- Overview and circuit description
- Fault code 1977 — reason, cause and effect
- Conditions for running the diagnostics
- Conditions for setting the fault code
- Action taken when the fault code is active
- Conditions for clearing the fault code
- Shop Talk — possible causes
- Associated procedures and guided troubleshooting steps
Cummins ISX11.9 code 1977 coverage
The aftertreatment fuel injector (doser) is controlled by the ECM through a pulse-width-modulated signal, and the amount of fuel injected depends on how long the signal is on. The procedure covers ISX11.9 CM2250 (2010-12) and ISX12 CM2250 (2010-12) engines and is shared across the CM2250 engine family listed in the associated procedures table. Cummins publishes the full specifications and service procedures for this engine family; see the manufacturer at Cummins.
The document lists the possible causes the factory tree checks:
- 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 or to a voltage source in the engine harness
- high resistance in the injector solenoid
Who needs this Cummins ISX11.9 code 1977 manual
Fleet technicians and workshop owners will use this guide to read the amber-lamp fault with the INSITE electronic service tool, inspect the aftertreatment fuel injector and its wiring, and decide whether the sensor, harness, or ECM is at fault. Confirm Cummins ISX11.9 code 1977 against live data before replacing any part, and follow the guided troubleshooting steps in the order the document gives them.
The full PDF is available in the DiagTechPro manuals library; a free account is required to download it.
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