Detroit Diesel
    DDEC flash code

    Detroit Flash Code 31: Aux. Output #4 Short to Ground (High Side) - T3

    31 on Detroit Diesel engines means: Aux. Output #4 Short to Ground (High Side) - T3. The failure mode (FMI 4) is “voltage below normal, or shorted to low source”.

    Code details

    Manufacturer
    Detroit Diesel
    Applies to
    Detroit Diesel Series 60 EGR (DDEC IV)
    Fault code
    31
    FMI
    4 — Voltage below normal, or shorted to low source
    J1587 PID / SID
    SID 52

    What to do next

    • Read active and inactive codes with the OEM service tool (Detroit Diesel Diagnostic Link) and note the occurrence count.
    • FMI 4 tells the shop the type of failure to test for: voltage below normal, or shorted to low source.
    • Have a heavy-duty diesel technician confirm the fault against the engine or chassis service manual before replacing parts.

    Get this code diagnosed

    Send one request and nearby diesel shops and mobile mechanics can quote the repair.

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    Related fault codes

    Source: Detroit Diesel Series 60 EGR Technician's Guide, DDEC IV EGR fault code table (Table 4-1). See also OBD-II codes.