Safe to driveTo the nearest safe stop
J1939 code SPN 803. Below — how the fault is worded at the factory by Ford Trucks, Renault Trucks and WABCO ABS/ESC, and what the second half of the code (FMI) means in the standard.
Ford TrucksRenault TrucksWABCO ABS/ESC
Ford Trucks/Ecotorq writes fault numbers in its own format: the code in the table below is a Ford code (hexadecimal, zero-padded), not a J1939 SPN. It matches the standard only where the signal itself is standard, and usually matches the title of this page by digit alone.
| FMI 9 | Lost Communication with TPMS (Tire Pressure Monitoring System) |
| FMI 2 | ABS unit: some functions faulty on the ground side. Repair: Check the continuity of the ABS unit wiring (X1/10, X1/11, X1/12). If the fault persists, replace the ABS unit. |
| FMI 3 | ABS unit: some functions faulty on the ground side. Repair: Check the continuity of the ABS unit wiring (X1/10, X1/11, X1/12). If the fault persists, replace the ABS unit. |
| FMI 4 | ABS unit: some functions faulty on the ground side. Repair: Check the continuity of the ABS unit wiring (X1/10, X1/11, X1/12). If the fault persists, replace the ABS unit. |
| FMI 3 | All ABVs Output Shorted to UBATT |
| FMI 4 | ECU Voltage is Too Low |
| FMI 5 | All ABVs High Impedance |
| FMI 6 | All ABVs Shorted to Ground |
| FMI 7 | Internal Voltage Supply |
Safe to drive. Below — how much time you have and what happens if you keep going.
The electrical system is not holding voltage. While the engine runs the alternator carries it; shut it off and you may not restart.
Next the lights go, then modules start dropping out and false codes appear all over the truck. Get to somewhere with help without shutting the engine down.
Check the battery terminals and earth strap — corrosion and loose clamps throw false codes all over the truck. Running voltage should be 27–29 V.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.