SPN 1071 FMI 4 is the Detroit DD Series fault-code troubleshooting sheet that documents a short to ground on the variable-speed fan control solenoid circuit on the Motor Control Module engine platform. This 3-page reference reproduces the fault-code identification and the factory decision tree so a technician can diagnose the concern before replacing parts.
Official document details
| Brand | Detroit |
|---|---|
| Model coverage | Detroit DD Series (EPA 2007-Current) |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Fault code | FMI 4 under SPN 1071 (ALL YEARS) |
| Source | Detroit fault-code literature via TruckFaultCodes.com, © 2017 |
| Pages | 3 |
| Format | |
| Language | English |
SPN 1071 FMI 4 fault description
This three-page sheet isolates a short to ground on the fan control solenoid circuit. With the ignition off, the technician disconnects the fan control solenoid and then the Motor Control Module (MCM) 120-pin connector. Resistance is measured from pin 1 of the fan control solenoid to ground; a reading of less than 10K ohms identifies a short to ground toward pin 33 of the MCM connector, while a higher reading points to a short between pin 2 of the solenoid and pin 91 of the MCM connector. The identified short is then repaired and the fix verified.
The SPN 1071 FMI 4 sheet identifies the following likely causes and check points:
- Short to ground between pin 1 of the solenoid and pin 33 of the MCM
- Short to ground between pin 2 of the solenoid and pin 91 of the MCM
Document table of contents
- Fault code identification
- Fan control solenoid disconnection
- Resistance-to-ground measurements
- Wiring short repair
Applicable truck models
This troubleshooting sheet applies to Detroit DD Series engines built from EPA 2007 to current that use the Motor Control Module (MCM) and Common Powertrain Controller architecture. Confirm the engine’s emissions family and calibration against the manufacturer’s official documentation at the Detroit engine website before repairs.
Who needs this SPN 1071 FMI 4 manual
Heavy-duty diesel technicians, fleet shops and mobile mechanics who retrieve this code on a Detroit DD engine need this manual to follow the factory decision tree instead of guessing. It is written for anyone using DDDL or an equivalent diesel diagnostic tool who wants the exact test values before condemning a component.
The full 3-page PDF of this procedure is available in the DiagTechPro manuals library; a free account is required to download.
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