SPN 625 FMI 4 is the Detroit DD Series diagnostic fault-code sheet (SPN 625 / FMI 4) that documents erratic data, or a failed Controller Area Network (CAN) proprietary data link between the Motor Control Module (MCM) and the Common Powertrain Controller (CPC). This 3-page PDF, drawn from the Detroit / Detroit Diesel Corporation (DDC) troubleshooting reference (© 2017), gives the workshop the exact measured checks needed to confirm and repair the fault rather than guess at it.
SPN 625 FMI 4 document details
| Brand | Detroit (Detroit Diesel Corporation) |
| Model coverage | DD Series (EPA 2007-Current); Series 60 (DDEC VI, EPA 2007) |
| System / Group | Diagnostic Trouble Codes (DTCs) – SPN 625 / FMI 4 |
| Source | Detroit / DDC diagnostic troubleshooting reference |
| Year / Revision | © 2017 |
| Pages | 3 |
| File size | 0.22 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code definition (SPN 625, FMI 4)
- Diagnostic note
- Troubleshooting steps 1 to 11
- MCM 21-pin connector voltage and resistance checks
- CPC #4 connector wiring checks
- Detroit Customer Support contact
Fault definition and diagnosis
The sheet opens by confirming whether the MCM or CPC was recently changed or reprogrammed, then has the technician disconnect the MCM 21-pin connector and measure battery voltage at pin 7. Later steps check resistance between pins 1 and 3 of the CPC #4 connector and the wiring back to pins 13 and 19 of the MCM 21-pin connector, isolating short-to-ground, short-circuit and open-circuit conditions.
Applicable truck models
It applies to Detroit DD Series engines (EPA 2007 to current) and the related Series 60 (DDEC VI, EPA 2007) platform that share the MCM and CPC control architecture. For engine specifications and authorised service information, see the official Detroit engine website.
Who needs the SPN 625 FMI 4 manual
Diesel technicians and workshop owners diagnosing this Detroit DTC with DiagnosticLink or ServiceLink use it to follow the manufacturer sequence step by step, and to confirm the SPN 625 / FMI 4 repair before returning the truck to service.
The full PDF is available in the DiagTechPro manuals library; a free account is required to download it.
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