SPN 1071 FMI 5 is the Detroit DD Series fault-code troubleshooting sheet that documents an open circuit on the variable-speed fan control solenoid output on the Motor Control Module engine platform. This 4-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 5 under SPN 1071 (ALL YEARS) |
| Source | Detroit fault-code literature via TruckFaultCodes.com, © 2017 |
| Pages | 4 |
| Format | |
| Language | English |
SPN 1071 FMI 5 fault description
The four-page procedure first checks whether SPN 647/FMI 5, SPN 1072/FMI 5 and this code are all active, which points to a shared open between pin 91 of the Motor Control Module (MCM) 120-pin connector and the fan and Jake Brake solenoids. If only this code is present, the technician runs the Fan Service routine and compares desired to actual fan speed, then measures voltage at the fan control solenoid connector. Depending on the readings, the fault resolves to a failed fan control solenoid or an open between the solenoid pins and pins 91 or 33 of the MCM connector.
The SPN 1071 FMI 5 sheet identifies the following likely causes and check points:
- Shared open toward pin 91 of the MCM when multiple codes are active
- Low voltage at the fan control solenoid connector
- Failed fan control solenoid
- Open between the solenoid and pin 91 or pin 33 of the MCM
Document table of contents
- Fault code identification
- Check for multiple codes
- Fan Service routine
- Fan control solenoid voltage checks
- Wiring open 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 5 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 4-page PDF of this procedure is available in the DiagTechPro manuals library; a free account is required to download.
Related manuals library
