This Detroit DEF valve circuit troubleshooting sheet documents fault code SPN 3363/FMI 4, Diesel Exhaust Fluid (DEF) Valve Circuit Failed Low, on Detroit DD Series engines. It inspects the DEF valve connector and measures harness resistance back to the ACM 120-pin connector. The monitored parameter is the DEF valve, with a 10% derate.
Official document details
| Brand | Detroit |
|---|---|
| Model coverage | DD Series diesel engines (DD13, DD15, DD16), EPA 2007 and newer |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Fault code | SPN 3363 / FMI 4 |
| Emission tier | EPA10 / GHG14 |
| Publication no. | Detroit Power Service Literature (via TruckFaultCodes.com, © 2017) |
| Pages | 2 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Detroit DEF valve circuit table of contents
- Fault code identification: SPN 3363, FMI 4
- Description: DEF valve, MIL/CEL lamps and 10% derate
- Steps 1-3: inspect the DEF valve connector pins
- Step 4: disconnect the ACM 120-pin connector
- Step 5: measure pin 1 harness resistance (1k ohm limit)
- Decision: repair wiring or replace the DEF valve
Applicable truck models
This procedure applies to Detroit DD Series diesel engines certified to EPA10 and GHG14 standards, covering the DEF valve and the wiring to pins 8 and 34 of the ACM 120-pin connector. A low reading points to a harness short rather than a failed valve. See Detroit’s official service literature portal for the authoritative Detroit repair procedures.
Who needs this Detroit DEF valve circuit manual
Technicians diagnosing a low DEF valve circuit will use this sheet to inspect connector pins and measure harness resistance before replacing the valve. It suits workshops repairing Detroit SCR dosing wiring.
The full PDF is available in the DiagTechPro manuals library — a free account is required to download. It is offered for reference alongside your Detroit diesel diagnostic tool. DiagTechPro catalogues Detroit fault-code documents so technicians can locate the exact SPN and FMI they are chasing without paging through a full engine service manual. Each entry lists the page count, file size and emission tier up front, and links to the closely related codes shown below so a diagnosis can move quickly from one fault to the next.
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