This SPN 84 FMI 5 reference covers a Detroit DD Series Vehicle Speed Sensor (VSS) open circuit, where the signal is broadcast to the Motor Control Module through the Common Powertrain Controller. It is part of the DiagTechPro truck manuals library and preserves the original TruckFaultCodes.com Detroit fault-code library (Copyright 2017).
Official document details
| Brand | Detroit |
|---|---|
| Model coverage | Detroit DD Series (EPA 2007-current) engines; the same fault-code procedure is also filed under the Detroit Series 60 (DDEC VI, EPA 2007) group. |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Fault code | SPN 84 / FMI 5 |
| Source | TruckFaultCodes.com Detroit fault-code library (Copyright 2017) |
| Pages | 1 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification (SPN 84, FMI 5)
- VSS open-circuit description
- Harness continuity measurements
- Sensor replacement criteria
Diagnostic steps in the SPN 84 FMI 5 document
After disconnecting the VSS, the technician measures resistance between CPC connector #3 (21-pin) pin 13 and VSS pin 1, then pin 14 to VSS pin 2; a reading above 3 ohms indicates an open wire to repair. A final measurement between CPC #3 pins 13 and 14 above 10 K ohms calls for replacing the VSS, otherwise a harness short is repaired.
The Vehicle Speed Sensor (VSS) open circuit condition on Detroit DD Series trucks is read and cleared with DiagnosticLink (formerly DDDL); the SPN and FMI pair identifies the exact circuit and failure mode. Confirm the code is active and capture freeze-frame data before running the pinpoint tests, then clear it and road-test the truck to verify the repair has held.
Applicable truck models and engines
This document applies to Detroit DD Series (EPA 2007-current) engines; the same fault-code procedure is also filed under the Detroit Series 60 (DDEC VI, EPA 2007) group. For factory service data, parts and warranty information, consult Detroit’s official DD engine support.
Who needs the SPN 84 FMI 5 manual
It is aimed at DD Series technicians confirming an open speed-sensor circuit before replacing the sensor or repairing the CPC harness.
The complete PDF is available in the DiagTechPro manuals library; a free account is required to download it.
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