SPN 1761 FMI 9 is the Detroit code set when the DEF tank signal is not available over the datalink, and this sheet walks the harness and Aftertreatment Control Module (ACM/ACM2.1) checks that isolate it. Follow it before replacing the sender.
Official document details
| Brand | Detroit |
| Model coverage | DD13, DD15, DD16 (EPA 2007-current) |
| System / group | DEF / SCR aftertreatment — level sensor circuit |
| Fault code | SPN 1761 / FMI 9 |
| Publication no. | Not printed on sheet |
| Year / revision | Reference dated 2017 |
| Pages | 2 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault header: SPN 1761 / FMI 9 — DEF tank signal not available via CAN
- Step 1 — ACM2.1 reprogramming and fuel-map check
- Steps 2-4 — power-down, key cycle and reconnect the tool
- Steps 5-8 — DEF tank header connector and 40-80 ohm reading
- Steps 9-11 — ACM2.1 terminating resistor and short checks
SPN 1761 FMI 9 troubleshooting steps
Step 1 asks whether the Aftertreatment Control Module (ACM2.1) was recently reprogrammed; if so, clearing the codes and verifying the correct fuel map may release the vehicle, because the ACM2.1 expects the DEF tank Controller Area Network (CAN) signal even though some vehicles are hardwired. If not, you cycle power, reconnect the tool, then measure across pins 1 and 2 of the DEF tank header — 40 to 80 ohms is good. Otherwise the ACM2.1 internal terminating resistor across pins 48 and 49 is checked (50-70 ohms), and the DEF CAN harness is tested for shorts to ground above 10K ohms before replacing the header or the ACM2.1.
Applicable truck models
This procedure covers Detroit DD-series engines — DD13, DD15 and DD16 on the EPA 2007-current platform with SCR aftertreatment — and shares its SPN/FMI structure with related Series 60 DDEC VI applications. Confirm the emissions calibration (EPA07, EPA10 or GHG14) before probing any pin. For engine serial-number and calibration confirmation, use the Detroit Diesel official support site.
Who needs the SPN 1761 FMI 9 manual
Diesel technicians and aftertreatment specialists use this sheet to test the DEF tank temperature/level sender wiring, distinguish a short or open from a failed sender, and identify the exact ACM pins before ordering parts.
The full PDF is available in the DiagTechPro manuals library; a free account is required to download. Source: Detroit SPN/FMI fault-code reference (© 2017); circuit values are measured with the Detroit Diesel Diagnostic Link (DDDL) and a calibrated multimeter.
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