SPN 158 FMI 2 is a Detroit™ ignition-switch diagnostic fault code, and this 2-page Detroit DD Series PDF documents the “Ignition Switch Not Plausible” condition in full. This code reports an implausible ignition-switch signal at the engine controllers. Diagnosis centres on ignition-supply voltage at the Motor Control Module 21-pin connector pin 7 and at the Common Powertrain Controller connector #2 pin 3, both of which should read greater than 11.5 volts. The summary below sets out the official causes, tools and troubleshooting order so a technician can verify the code before downloading the complete manual.
Official document details
| Brand | Detroit |
| Model coverage | DD Series (EPA 2007-Current) |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Publication no. | Not printed on sheet (Detroit™ via TruckFaultCodes.com, © 2017) |
| Year / Revision | 2017 |
| Pages | 2 |
| File size | 0.3 MB |
| Format | |
| Language | English |
SPN 158 FMI 2 document contents
- Fault code identification (SPN and FMI)
- Active vs inactive fault check
- MCM 21-pin connector voltage check
- CPC connector #2 voltage check
- Repair guidance and support escalation
Applicable truck models
The procedure applies to Detroit DD Series engines across all model years that use a Motor Control Module and Common Powertrain Controller. Only a multimeter and the diagnostic tool are required. For factory service data, wiring diagrams and bulletins beyond this fault-code sheet, consult the official Detroit Diesel support site.
Who needs this SPN 158 FMI 2 manual
Technicians chasing an intermittent ignition-switch or hard-start complaint on a Detroit engine need this sheet to isolate low or missing key-on voltage before condemning a controller. It also documents when to call the Customer Support Center at 800-445-1980.
You confirm whether the code is active, then measure key-on voltage at MCM pin 7 and CPC #2 pin 3; a reading under 11.5 volts points to a supply-circuit repair, while good voltage with an active fault directs you to escalate.
The full 2-page PDF is available in the DiagTechPro manuals library; a free account is required to download it. Every document in the library is indexed by suspect parameter number and failure mode identifier, so you can cross-reference related Detroit DD Series fault codes without leaving the page.
Related manuals library
Sản phẩm liên quan cho hãng này
Cùng brand theo taxonomy hiện có trong catalog WooCommerce.
Detroit Diesel Reports 6.3
Detroit Reprogramming Station (DDRS) 7.11
DDDL Backdoor Password: A Comprehensive Guide
