The Detroit tachograph speed signal troubleshooting sheet documents Detroit fault code SPN 1624 FMI 19, which sets when the tachograph vehicle speed signal is erratic on the J1939 data link. This 2-page PDF belongs to the Detroit DD Series (EPA 2007-Current) DTC library and guides a technician through the confirmation and repair sequence for the code. It is drawn from Detroit Power Service Literature and republished by TruckFaultCodes.com (2017).
The sheet first has the technician rule out related faults — Common Powertrain Controller (CPC) battery-voltage codes under SPN 168 and Motor Control Module CAN-line codes under SPN 625/FMI 9 — then checks whether the CPC was recently reprogrammed before using ServiceLink to review which modules are configured for the vehicle and their communication status.
Detroit tachograph speed signal document details
| Brand | Detroit |
| Model coverage | DD Series (EPA 2007-Current) |
| System / Group | Diagnostic Trouble Codes (DTCs) |
| Fault code | SPN 1624 FMI 19 |
| Source | Detroit Power Service Literature |
| Pages | 2 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification (SPN and FMI)
- Multiple-code check — CPC battery voltage (SPN 168)
- MCM CAN line check (SPN 625 / FMI 9)
- CPC reprogramming and configuration
- ServiceLink module communication check
Applicable truck models
This fault code troubleshooting procedure applies to Detroit DD Series engines built to EPA 2007 and later emissions standards, covering all model years within the DD Series DTC set. Use it alongside a diesel diagnostic tool such as DiagnosticLink or ServiceLink to read live data and confirm the code before any parts are replaced. For engine coverage and official service resources, visit the Detroit Diesel official website.
Who needs this Detroit tachograph speed signal manual
Fleet technicians, mobile diesel mechanics and workshop owners rely on this reference before opening the SPN 1624 FMI 19 code with a scan tool. Following the documented sequence avoids replacing good parts and clarifies whether the concern lies in wiring, a sensor, or a mechanical component.
The full SPN 1624 FMI 19 PDF is available in the DiagTechPro manuals library; a free account is required to download.
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