This Cummins CM550 375 document is a 3-page diagnostic procedure for Fault Code 375, covering an ECM fuel calibration corrupted condition. It explains the fault description, ECM and VP44 fuel pump checks, harness inspection, recalibration, and final fault-code clearing steps.
Official Cummins CM550 375 document details
| Brand | Cummins |
|---|---|
| Model coverage | ISB CM550 (1990-94) |
| System/Group | DTCs; Electronic Control Module (ECM) fuel calibration corrupted |
| Publication no. | Not specified |
| Year/Revision | Unknown |
| Pages | 3 |
| File size | 0.1 MB |
| Format | |
| Language | English |
Document table of contents
- FAULT CODE: 375
- PID: P0602, S254
- FMI: 2
- ELECTRONIC CONTROL MODULE (ECM) FUEL CALIBRATION CORRUPTED
- DESCRIPTION
- COMPONENT LOCATION
- TROUBLESHOOTING STEPS
- Step 1A) Turn key switch ON and check to see if the fault code is active at engine start-up
- Step 2A) Disconnect the engine harness from the fuel pump
- Step 3A) Install the VP44 fuel pump diagnostic tool, Part Number 3163834
- Step 4A) Inspect the engine harness and fuel pump solenoid leads for tampering
- Step 5A) Recalibrate the ECM with updated calibration code
- Step 6A) Disable the fault code and verify Fault Code 375 is inactive
- Step 6B) Clear the inactive fault codes using the diagnostic tool
Applicable truck models
This file applies to Cummins ISB CM550 (1990-94) engines using the diagnostic logic described for Fault Code 375. The procedure concerns the Electronic Control Module, ECM calibration data, VP44 fuel pump harness supply voltage, and the fuel pump control response to out-of-range commanded values. For current manufacturer information, visit Cummins official website.
Who needs this Cummins CM550 375 manual
This Cummins CM550 375 manual is intended for mechanics, diagnostic technicians, and workshop owners who need a short procedure for an active or high-count inactive Fault Code 375. It is useful when checking for illegal calibration tampering, aftermarket performance upgrade kits, ECM recalibration requirements, or remaining active fault codes after repair.
The extract states that the ECM contains calibration-specific parameters for engine performance and diagnostics, while the fuel pump has its own calibration to interpret ECM messages and control the pump. If the fueling calibration in the ECM is altered or tampered with, the code can be logged to protect the fuel pump from excessive duty cycles. The procedure directs the technician to read fault codes, measure supply voltage at pin 7 of the VP44 fuel pump harness connector to engine block ground, use the VP44 fuel pump diagnostic tool, inspect harness and solenoid leads, recalibrate the ECM with updated calibration code, and then verify that Fault Code 375 is inactive.
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