Detroit fault code SPN 3031 FMI 19 is the TruckFaultCodes.com diagnostic sheet for the DEF Tank Temperature Signal Erratic via CAN condition on Detroit DD-series engines. This 2 pages reference lists the fault identification, monitored conditions where shown, and the step-by-step troubleshooting the technician follows in the shop.
Official document details
| Brand | Detroit |
|---|---|
| Model coverage | Detroit DD Series (EPA 2007-Current) |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Publication no. | Not printed; TruckFaultCodes.com reference |
| Year / Revision | 2017 |
| Pages | 2 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification (SPN 3031 / FMI 19)
- ACM2.1 reprogramming and fuel map
- DEF tank header resistance checks
- ACM2.1 terminating resistor test
- Harness short-to-ground check
SPN 3031 FMI 19 troubleshooting steps
The two-page routine first checks whether the ACM2.1 was recently reprogrammed and confirms the correct fuel map, since the module expects the Diesel Exhaust Fluid (DEF) tank signal over CAN. After a power-down cycle, resistance across pins 1 and 2 of the DEF tank header harness connector is measured and compared against the 60 plus or minus 20 ohm target. The ACM2.1 120-pin internal terminating resistor across pins 48 and 49 is checked at 60 plus or minus 10 ohms, and resistance to engine ground is confirmed above 10k ohms before the DEF tank header or ACM2.1 is replaced.
Applicable truck models
This sheet applies to Detroit DD-series diesel engines (the DD13, DD15 and DD16 family) built under the EPA 2007-Current emissions platform, in its GHG14 calibration. Engine and emissions specifications should always be confirmed against the vehicle build; full engine information is published on the Detroit Diesel official site.
Who needs this SPN 3031 FMI 19 manual
Technicians tracing an erratic DEF tank temperature signal over the CAN bus use this sheet to isolate a shorted DEF harness from a failed tank header or ACM2.1. It is a quick bench reference rather than a full workshop manual, so the named removal steps still route back to Power Service Literature and, where escalation is needed, to the Detroit Customer Support Center.
The full PDF is available in the DiagTechPro manuals library; a free account is required to download it.
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