Do not driveTo the nearest safe stop
J1939 code SPN 1066. Below — how the fault is worded at the factory by Knorr-Bremse EBS, MAN, Meritor (ex-WABCO) and Renault Trucks, and what the second half of the code (FMI) means in the standard.
Knorr-Bremse EBSMANMeritor (ex-WABCO)Renault Trucks
| FMI 0 | Module foot brake. Undefined fault |
| FMI 3 | Module foot brake. Not identified |
| FMI 7 | Module foot brake. Short |
| FMI 8 | Module foot brake. Wrong signal |
| FMI 0 | Module foot brake - Undefined fault |
| FMI 3 | Module foot brake - Not identified |
| FMI 7 | Module foot brake - Short |
| FMI 8 | Module foot brake - Wrong signal |
| FMI 0 | Detection of Invalid Offset Value of Brake Signal |
| FMI 2 | Detection of Significant PWM Input Signal Difference |
| FMI 12 | Detection of Total Failure of both PWM Input Signals |
| FMI 2 | Open circuit or short on one of the two signals from the brake valve. Repair: Check the continuity of the wiring. |
Do not drive. Stop as soon as it’s safe to do so — don’t keep going.
The code is flagged critical: the manufacturer considers it unsafe to keep driving without checking.
This code alone cannot say what will fail next, so stop at the first safe opportunity and look at it on the spot.
That said, the manufacturer flags this code as critical — if in doubt, it is safer to stop and check on the spot.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.