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SPN 798 — ABS Pressure Modulator Valve, Axle 2, Right

Do not driveMinutes

J1939 code SPN 798. Below — how the fault is worded at the factory by Bendix ABS/ESP, Meritor (ex-WABCO), Renault Trucks and WABCO ABS/ESC, and what the second half of the code (FMI) means in the standard.

Bendix ABS/ESPMeritor (ex-WABCO)Renault TrucksWABCO ABS/ESC

Bendix ABS/ESP

FMI 3DA Right PMV HLD Solenoid Shorted to Voltage; AA Left PMV REL Solenoid Shorted to Voltage
FMI 4DA Right PMV HLD Solenoid Shorted to Ground; DA Right PMV REL Solenoid Shorted to Ground
FMI 5DA Right PMV CMN Open Circuit; DA Right PMV HLD Solenoid Open Circuit; DA Right PMV REL Solenoid Open Circuit
FMI 13DA Right PMV Configuration Error

Meritor (ex-WABCO)

FMI 3Failure detection 'ShortUb' at AbsInlet/ AbsOutlet (Drive Axle Right)
FMI 4Failure detection 'ShortGnd' at AbsInlet/AbsOutlet (Drive Axle Right)
FMI 5Failure detection 'Interruption' at AbsInlet/AbsOutlet (Drive Axle Right)
FMI 13Failure detection 'OverEquipped' at AbsInlet/AbsOutlet (Drive Axle Right)

Renault Trucks

FMI 2ABS valve, rear right, does not meet requirements. Repair: Check that the ABS valve is the correct one.
FMI 3ABS valve, rear right, inlet and outlet valves, short circuit. Repair: Check the continuity of the ABS valve wiring (X4/10, X4/11, X4/12).
FMI 4ABS valve, rear right, inlet and outlet valves, short to ground. Repair: Check the continuity of the ABS valve wiring (X4/10, X4/11, X4/12).
FMI 5ABS valve, rear right, short on one of the supply wires. Repair: Check the continuity of the ABS valve wiring (X4/10, X4/11, X4/12).
FMI 12Rear circuit pneumatic fault or module internal fault. Repair: Check the module inlet and outlet for air leaks. Check the air lines for contamination and kinks. Check the exhaust at the valve and at the module with a PC. Check the minimum pressure switches.

WABCO ABS/ESC

FMI 3Shorted to UBATT
FMI 5Open Circuit
FMI 6Shorted to Ground

What FMI means in J1939

SPN 798 FMI 2798/2 · 798.2data erratic or intermittent
SPN 798 FMI 3798/3 · 798.3voltage above normal or shorted high
SPN 798 FMI 4798/4 · 798.4voltage below normal or shorted to ground
SPN 798 FMI 5798/5 · 798.5current below normal or open circuit
SPN 798 FMI 6798/6 · 798.6current above normal or grounded circuit
SPN 798 FMI 12798/12 · 798.12faulty device or component
SPN 798 FMI 13798/13 · 798.13calibration out of range

Can I keep driving

Do not drive. Stop as soon as it’s safe to do so — don’t keep going.

What happens if you keep driving

Time you have: Minutes

Part of the brake circuit or ABS/EBS is out of service. The pedal may still feel normal — until the first emergency stop or descent.

Next comes longer stopping distance, a skid on a slick surface, failure on a long downgrade. This is the case where "I will take it slow" does not work.

What to check on the spot

Let the air system build to working pressure and listen for leaks. Don’t drive with faulty brakes.

Nearby: brakes

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