SPN 4375 FMI 4 is the Detroit DD Series (EPA 2007–Current) diagnostic trouble code that Detroit documents as “Diesel Exhaust Fluid (DEF) Pump Circuit Failed Low”. This 2-page GHG14 fault-code sheet documents the circuit description and the DEF pump connector pinout, the dash-lamp indication and engine reaction, and the ordered troubleshooting steps used to confirm and clear the condition. The fault indicates the DEF pump control circuit is shorted low, and the sheet gives the four-pin DEF pump connector pinout and a wiggle test on the ACM2.1 120-pin connector to find a short to ground before the pump is replaced, verified by the ADS Self-Check.
SPN 4375 FMI 4 document details
| Brand | Detroit (Detroit Diesel) |
|---|---|
| Model coverage | Detroit DD Series (EPA 2007-Current) engines |
| System / group | DD Series (EPA 2007-Current) / DTCs |
| Publication / source | Detroit Power Service Literature (TruckFaultCodes reference, 2017) |
| Emissions family | GHG14 |
| Pages | 2 |
| File size | 0.24 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code description
- DEF pump harness disconnection and pin inspection
- DEF pump four-pin connector pinout
- Active-fault verification with the pump disconnected
- ACM2.1 120-pin wiggle test and short-to-ground repair
- ADS Self-Check verification
Applicable truck models
This fault-code procedure applies to trucks powered by the Detroit DD Series (EPA 2007-Current) engines on the DD Series (EPA 2007–Current) platform. The technician disconnects the DEF pump harness connector, inspects the pins, clears codes and rechecks whether the fault stays active with the pump disconnected, then wiggle-tests the ACM2.1 120-pin connector and repairs the short to ground between pin 3 of the pump connector and pin 20 of the ACM2.1 before running the ADS Self-Check to verify the repair. Always confirm the engine family and GHG14 emissions level against the vehicle, and cross-check the latest procedure in the Detroit Power Service Literature on the official Detroit website.
Who needs this SPN 4375 FMI 4 manual
Diesel technicians, fleet maintenance teams and workshop owners diagnosing a low-side DEF pump circuit fault or an SCR dosing fault on Detroit DD Series trucks use this sheet to work the fault in order instead of guessing. The disconnect-and-recheck logic quickly separates a shorted harness from a failed DEF pump.
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