SPN 698 FMI 5 is the Detroit DD Series diagnostic fault code that identifies Grid heater circuit failed open. This DiagTechPro reference summarizes the official 3-pages Detroit diagnostic sheet so a technician can confirm the condition before opening the truck, and it links to the full downloadable PDF.
Official document details
| Brand | Detroit |
| Model coverage | Detroit DD Series (EPA 2007-Current) diesel engines |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Fault condition | Grid heater circuit failed open |
| Published source | TruckFaultCodes.com, Copyright © 2017 |
| Pages | 3 |
| File size | 0.2 MB |
| Format | |
| Language | English |
SPN 698 FMI 5 diagnostic overview
This Detroit EPA07 sheet covers a grid heater circuit that failed open. The technician disconnects the grid heater harness connector, turns the ignition on, and measures voltage at pins 2 and 3 of the connector, taking the first reading within the first minute of key on. Depending on the readings, resistance is measured back to the Motor Control Module 120-pin connector at pins 92, 41 and 79, and open or short circuits are repaired; if the wiring is good the EPA07 grid heater is replaced per Power Service Literature.
Document table of contents
- Fault code identification
- Grid heater harness voltage checks
- MCM 120-pin connector resistance checks
- EPA07 grid heater replacement reference
Applicable truck models covered
This diagnostic applies to Detroit DD Series EPA07 diesel engines that use an intake grid heater for cold-start assistance, and is grouped with the Series 60 (DDEC VI – EPA 2007) DTCs. It covers the heater element and its harness back to the Motor Control Module. For the OEM wiring schematics referenced in this procedure, see the official Detroit engine manufacturer site.
Who needs the SPN 698 FMI 5 manual
Workshop technicians and fleet owners using the diesel diagnostic tool to read Detroit fault codes and test the grid heater circuit and Motor Control Module wiring will need this sheet. The full step-by-step PDF is available in the DiagTechPro manuals library, and a free account is required to download it.
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