Cummins M11 code 321 is the official Cummins injector circuit troubleshooting chart that guides a technician through fault code 321 on M11 CELECT Plus (1995-98) engines. This 1-page PDF from the Cummins service literature explains the injector solenoid circuit, its component location, and the measured checks that confirm the repair before the yellow warning lamp is cleared.
Official document details
| Brand | Cummins |
|---|---|
| Model coverage | M11 CELECT Plus (1995-98) |
| System / Group | Injector Circuit |
| Fault code | Code 321 · PID S004 · SPN 737 · FMI 6 |
| SRT operation | 00-604 |
| Warning lamp | Yellow |
| Year / Revision | Copyright 2017 |
| Pages | 1 |
| File size | 0.1 MB |
| Format | |
| Language | English |
Document table of contents
- Circuit description
- Component location
- Shop talk – possible causes
- Troubleshooting steps
- Fault code verification and clearing
Cummins M11 code 321 troubleshooting summary
The injector solenoid valves are actuated by the electronic control module (ECM) to control fuel metering and timing. Each injector solenoid connects to the ECM through a supply wire and a return wire, and the ECM sends an electrical pulse that closes the normally open valve during injection and metering. On the M11 a two-piece actuator harness joins an external harness at the ECM C connector port to an internal harness running inside the rocker lever housing, with one connector for each injector solenoid. The document works through labelled troubleshooting steps that inspect the connector pins, measure circuit resistance, check for an open circuit and a short circuit to engine block ground, and verify that fault code 321 is inactive after the repair.
Referenced Cummins service items include electronic contact cleaner, Part Number 3824510, and the SRT operation number 00-604 printed on the cover. The chart pairs each measurement with a pass or fail branch so the technician replaces the injector solenoid wire, the pass-thru connector, the actuator harness or the injector only when the reading confirms it.
Applicable truck models
This procedure applies to Cummins M11 CELECT Plus (1995-98) engines as fitted to Class 8 highway trucks. Always confirm the engine dataplate and control parts list before servicing. Full engine data and dealer support are available on the Cummins official website.
Who needs this Cummins M11 code 321 manual
Heavy-duty diesel technicians, fleet service managers and independent workshop owners diagnosing this injector fault rely on the manufacturer procedure instead of swapping parts by guess. The same injector solenoid circuit logic covers the other injector fault codes in the M11 CELECT Plus (1995-98) family, so one reference supports several diagnostic bays.
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Applies to these truck models
This is the manufacturer document shared across 2 model families. It applies to:
- Cummins DTCs
- Cummins M11 CELECT Plus (1995-98)
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