This 5V sensor supply high sheet covers Detroit SPN 3509 FMI 3 on the MCM2.1, set when the Motor Control Module detects a short to power above 5.3 volts on its shared reference. It lists every sensor that shares the reference and shows how to isolate the shorted branch. Use it before condemning the module.
Official document details
| Brand | Detroit |
|---|---|
| Model coverage | DD Series (EPA 2007-Current); also filed under Series 60 (DDEC VI – EPA 2007) |
| System / Group | DTCs — 5V Sensor Supply Bank 1 Circuit Failed High |
| Fault code | SPN 3509 / FMI 3 |
| Source | www.TruckFaultCodes.com (© 2017) |
| Pages | 2 |
| File size | 0.2 MB |
| Format | |
| Language | English |
5V sensor supply high diagnostic guide
The document maps MCM2.1 pins 58, 82, 85 and 117 to the sensors that share the reference, including the crankcase ventilator speed, fuel rail pressure, water pump speed, oil pressure, camshaft position, fan speed and intake throttle valve sensors. With the diagnostic tool connected, each component is disconnected one at a time while the fault is watched; if it clears, that part is replaced. Disconnecting the 120-pin connector then decides between a harness repair and replacing the module.
Document table of contents
- Fault code identification: SPN 3509, FMI 3
- Description, monitored parameter and enabling conditions
- MCM2.1 pin-to-sensor reference chart
- Step-by-step troubleshooting procedure
- Harness repair or module replacement
Applicable truck models
This procedure applies to Detroit DD Series engines built for EPA 2007 and later, covering GHG14 calibrations as printed on the document cover, and the identical SPN/FMI sheet is also filed under Detroit Series 60 (DDEC VI, EPA 2007). Confirm the emissions platform on your truck and cross-check the connector and pin numbers against the official Detroit engine support site before making any repair.
Who needs this 5V sensor supply high manual
A driveability technician chasing several sensor codes at once on a GHG14 Detroit engine relies on this reference to find the one shorted branch on the shared reference rather than replacing sensors at random.
The full 2-page PDF is available in the DiagTechPro manuals library; a free account is required to download.
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