This Cummins idle validation switch reference documents Fault Code 551 (PID P091, SPN 91, FMI 4, SRT 00-611) for the Integrated Sensor/Switch (ISS) version on the M11 CELECT Plus. The 6-page yellow-lamp sheet explains how the ECM reads pedal position.
Official document details
| Brand | Cummins |
|---|---|
| Model coverage | M11 CELECT Plus (1995-98) |
| System / group | Idle Validation Switch Circuit |
| Fault code | 551 (ISS) |
| PID / SPN | P091 / SPN 91 |
| FMI | 4 |
| Diagnostic lamp | Yellow |
| SRT | 00-611 |
| Pages | 6 |
| File size | 0.3 MB |
| Format | |
| Language | English |
| Source | Cummins fault code reference (TruckFaultCodes.com, 2017) |
Document table of contents
- Circuit description
- Component location
- Shop talk diagnostic notes
- Step-by-step troubleshooting
- Fault verification and clearing codes
Cummins idle validation switch checks
The switch tells the ECM when the accelerator pedal is released (on-idle) or depressed (off-idle), and it is factory-adjusted to change state at the correct pedal position. On this ISS variant the switch is built into the accelerator pedal assembly. Shop talk attributes Code 551 mainly to a loose connection, an uncalibrated pedal, or a mis-wired switch, and notes that breakout cable part number 3824892 is required to check voltage levels. If wiring and sensor checks pass, the manual directs replacing the circuit wires between pedal and ECM, routing them around the bulkhead, and re-sealing openings to keep fumes out of the cab.
Applicable truck models
Coverage is the Cummins M11 CELECT Plus (1995-98) with the ISS accelerator pedal assembly. The ECM and pedal must be electrically calibrated together; confirm the procedure on the official Cummins website.
Who needs this idle validation switch manual
Technicians resolving throttle, idle, or pedal-calibration complaints on M11 CELECT Plus trucks with the Integrated Sensor/Switch pedal will find the tests here.
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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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