This Detroit coolant outlet high reference documents fault code SPN 110/FMI 3 (Engine Coolant Outlet Temperature Circuit Failed High) for Detroit DD-series engines with the 120-pin MCM harness. It reproduces the original TruckFaultCodes.com fault tree, from the first check through the final repair, so the code can be confirmed and worked in the exact order the factory intended. Each step lists the measured value or check and the pass or fail branch that follows, matching the layout used in the source document.
Detroit coolant outlet high troubleshooting overview
This is the full circuit-failed-high tree. After a companion-code check it has the technician disconnect the coolant-outlet sensor, measure 2.8 to 3 volts across pins 1 and 2, then trace opens and shorts back to MCM pins 55 and 110. A separate branch covers a short to power on MCM pins 77, 80, 108 or 110. Follow the checks in sequence and verify the repair before clearing the code and releasing the vehicle.
Official document details
| Brand | Detroit |
| Model coverage | Detroit DD-series engines with the 120-pin MCM harness |
| System / group | DTCs — engine coolant outlet temperature sensor circuit |
| Fault code | SPN 110/FMI 3 |
| Source publication | TruckFaultCodes.com (© 2017) |
| Pages | 2 |
| File size | 0.3 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification — SPN 110/FMI 3
- Monitored parameter and enabling conditions
- Companion-code check (SPN 174, 175 and 4076 FMI 3)
- Sensor voltage measurement (2.8–3 V across pins 1 and 2)
- Harness repairs to MCM pins 55 and 110; short-to-power on pins 77/80/108/110
Applicable truck models
It applies to Detroit DD-series engines with the 120-pin MCM harness shared by the coolant, oil and fuel temperature sensors. Always cross-check the reading against any companion codes before condemning a component. For the official product and service literature, visit the Detroit Diesel website.
Who needs this Detroit coolant outlet high manual
Technicians who need the voltage thresholds and pin numbers to repair a coolant-outlet circuit failed high. It is written for shop use as a quick, printable reference to keep beside a diesel diagnostic tool during the job.
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