SPN 986 FMI 13 is the Detroit DD Series diagnostic sheet that explains j1939 cm1 signal from source #1 or #2 missing on EPA10 and GHG14 engines. The fault sets when the Common Powertrain Controller (CPC) receives a J1939 CM1 message but the requested fan percent speed signal is not available. Detroit is explicit that this does not point to a CPC failure and the controller should not be replaced. The sheet directs the technician to first check for battery-voltage codes (SPN 168) and an MCM SPN 625 CAN code, then confirm CPC configuration and use ServiceLink to inspect module communication. This DiagTechPro library page outlines what the 2 pages PDF contains before you download it.
SPN 986 FMI 13 document details
| Brand | Detroit |
|---|---|
| Model coverage | Detroit DD Series (EPA 2007–Current) |
| System / group | J1939 datalink / requested fan speed |
| Fault code (SPN / FMI) | 986 / 13 |
| Fault type | J1939 CM1 signal from source #1 or #2 missing |
| Emissions platform | EPA10 and GHG14 |
| Source | TruckFaultCodes.com (Copyright © 2017) |
| Pages | 2 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification (SPN and FMI reference)
- Fault description and datalink source
- Multiple-code check (battery voltage and CAN)
- Module configuration check with ServiceLink
- Communication troubleshooting procedure
Applicable truck models and engines
This fault sheet applies to Detroit DD Series engines built to the EPA10 and GHG14 emissions platform. It is used with the Detroit diesel diagnostic tool, and with ServiceLink where module configuration must be confirmed. Detroit publishes these fault codes through TruckFaultCodes.com, and the same SPN can appear on more than one module, so confirm the reading before ordering parts. For engine coverage and official service literature, see the Detroit official support site.
Who needs the SPN 986 FMI 13 sheet
Fleet technicians and Detroit-certified workshops troubleshooting this J1939 datalink fault need this sheet to follow the correct checks instead of guessing at parts. The procedure ends at the forward HVAC control module or the Modular Switch Field (MSF) modules, so it suits technicians using ServiceLink to confirm which modules are configured on the vehicle.
The complete 2 pages PDF is available in the DiagTechPro manuals library; a free account is required to download it.
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