The SPN 986 FMI 19 document is a Detroit DD Series diagnostic trouble code guide covering the J1939 CM1 SPN 986 requested fan percent speed signal that is erratic condition and its step-by-step troubleshooting. This 2 pages PDF is compiled from the TruckFaultCodes.com Detroit fault codes reference (© 2017) for the DD Series (EPA 2007-Current) / DTCs set. It is written for workshop diagnostics rather than general reading.
Official document details
| Brand | Detroit |
| Model coverage | Detroit DD Series (EPA 2007-Current) engines |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Diagnostic trouble code | SPN 986/FMI 19 — J1939 CM1 Signal From Source #1/#2 Erratic |
| Publication no. | Not stated (TruckFaultCodes.com DTC reference) |
| Year / Revision | © 2017 |
| Pages | 2 |
| File size | 0.2 MB |
| Format | |
| Language | English |
SPN 986 FMI 19 document sections
- Fault code identification: SPN 986/FMI 19 — J1939 CM1 signal from source #1 or #2 is erratic
- Notice: this fault does not indicate a CPC issue — do not replace the CPC
- Checking for multiple codes: CPC SPN 168/FMI 0/14/18 battery voltage faults
- Checking for MCM SPN 625/FMI 9 CAN line faults
- Using ServiceLink to confirm module configuration after CPC reprogramming
Applicable truck models covered
The SPN 986 FMI 19 fault applies to trucks fitted with Detroit DD Series (EPA 2007-Current) engines and the associated Common Powertrain Controller and Motor Control Module modules, covering EPA10 and GHG14 calibrations. The procedure references Common Powertrain Controller, Motor Control Module, ServiceLink and CAN line, and works through checking related battery-voltage and CAN codes and confirming CPC configuration; the CPC should not be replaced. Confirm the engine and emissions configuration against the vehicle build before ordering parts; verify current procedures on the Detroit Diesel official site.
Who needs this SPN 986 FMI 19 manual
This reference suits Detroit-certified technicians and fleet workshop owners diagnosing the J1939 CM1 SPN 986 requested fan percent speed signal that is erratic condition on DD Series engines. Every troubleshooting step and decision branch from the original PDF is preserved so the on-vehicle diagnosis can be followed in sequence, and the document names the exact connectors, pins and modules involved. Use it alongside a Detroit-compatible scan tool such as DDDL or DDRS.
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