The Cummins M11 code 255 troubleshooting document is a 4-page factory-style fault code guide covering the supply circuit (PID S026, SPN 701, FMI 3) on Cummins CELECT engines. This document covers the ECM output supply wiring that feeds the fuel shutoff valve, fan clutch and engine brake enable circuits, where externally supplied voltage on these wires can keep the outputs energised. It reproduces the circuit description, component location and the full step-by-step diagnostic procedure a technician follows to confirm the fault and verify the repair. The guide moves through connector inspection, harness continuity and resistance measurements, sensor and ECM checks, and then explains how to disable, re-run and clear the code once the repair has been confirmed on a diagnostic tool.
Cummins M11 code 255 document details
| Brand | Cummins |
| Model coverage | M11 CELECT (1990-94) |
| System / Group | Supply Circuit |
| Fault code identifiers | Fault Code 255 · PID S026 · SPN 701 · FMI 3 · Yellow lamp · SRT 00-603 |
| Source publication | TruckFaultCodes.com (Copyright 2017) |
| Year / Revision | 1990-94 platform |
| Pages | 4 |
| File size | 0.3 MB |
| Format | |
| Language | English |
Document table of contents
- Circuit Description
- Component Location
- Troubleshooting Steps
- Fault Code Verification and Clearing
Applicable truck models
This procedure applies to trucks running Cummins M11 CELECT (1990-94) with CELECT electronic controls. Technicians should confirm the engine dataplate and ECM calibration first, and cross-check every pin and connector location against the OEM wiring diagram, because connector positions vary with the chassis manufacturer. For engine-level specifications and authorised repair locations, see the Cummins official engine support site.
Who needs this Cummins M11 code 255 manual
This M11 code 255 manual is written for heavy-duty diesel technicians, fleet maintenance staff and workshop owners who want a repeatable diagnostic path instead of guesswork. It suits anyone reading Fault Code 255 as an active or inactive code and wanting to inspect the ECM output supply circuit, take the specified resistance and voltage readings, and confirm the ECM and harness before replacing parts.
Applies to these truck models
This is the manufacturer document shared across 2 model families. It applies to:
- Cummins DTCs
- Cummins M11 CELECT (1990-94)
Related manuals library
The complete Cummins Fault Code 255 PDF (4 pages) is available in the DiagTechPro manuals library; a free account is required to download the full document.
