This fault processing computer chip guide covers Cummins Fault Code 343 (PID S254, SPN 629, FMI 12, SRT 00-606) on the M11 CELECT Plus. The 5-page yellow-lamp document deals with an internal ECM processor that watches the injector outputs.
Official document details
| Brand | Cummins |
|---|---|
| Model coverage | M11 CELECT Plus (1995-98) |
| System / group | Fault Processing Computer (FPC) Chip |
| Fault code | 343 |
| PID / SPN | S254 / SPN 629 |
| FMI | 12 |
| Diagnostic lamp | Yellow |
| SRT | 00-606 |
| Pages | 5 |
| File size | 0.2 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
Fault processing computer chip diagnosis
The fault processing computer (FPC) is a processing chip inside the ECM that monitors the outputs to the injectors and reports error data to the main microprocessor over a communications link. Shop talk points to loose engine or chassis ground connections as a common cause of Code 343 and of intermittent stumble complaints, with special attention to the negative starter post connection, and warns that moisture in the ECM connectors can also log the fault. A damaged EPS can log Code 343 along with Codes 121 and 115, and defective alternators occasionally cause it — running the engine with the alternator belt off and seeing the code go inactive points to the alternator. Intermittent battery shorts to ground can also trigger it.
Applicable truck models
Coverage is the Cummins M11 CELECT Plus (1995-98) ECM and its grounds. Confirm ground and connector service points on the official Cummins website.
Who needs this processing computer chip manual
Technicians chasing intermittent stumble, ground faults, or alternator-induced ECM codes on M11 CELECT Plus trucks use this diagnostic guidance.
The full PDF is available in the DiagTechPro manuals library; a free account is required to download.
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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