SPN 2581 — Hydraulic Brake Circuit 2 Pressure

Do not driveMinutes

J1939 code SPN 2581. Below — how the fault is worded at the factory by Meritor (ex-WABCO), and what the second half of the code (FMI) means in the standard.

Meritor (ex-WABCO)

FMI 3	Pump Motor — Pump motor operates when not expected
FMI 4	Pump Motor — Pump motor does not switch on
FMI 5	Pump Motor — Supply voltage for pump motor missing
FMI 7	Pump Motor — Pump motor does not turn
FMI 12	Pump Motor — Relay voltage missing

What FMI means in J1939

SPN 2581 FMI 32581/3 · 2581.3	voltage above normal or shorted high
SPN 2581 FMI 42581/4 · 2581.4	voltage below normal or shorted to ground
SPN 2581 FMI 52581/5 · 2581.5	current below normal or open circuit
SPN 2581 FMI 72581/7 · 2581.7	mechanical system not responding
SPN 2581 FMI 122581/12 · 2581.12	faulty device or component

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

• SPN 1243ABS Fully Operational
• SPN 1351Air Compressor State
• SPN 1438ABS/EBS Amber Warning Signal
• SPN 1439EBS Red Warning Signal
• SPN 1725Air Spring Pressure, Front Axle, Left
• SPN 1727Air Spring Pressure, Rear Axle, Left
• SPN 1792Trailer ABS Warning Signal on Tractor
• SPN 2584Hydraulic Brake Circuit 1 Pressure Warning Status
• SPN 4000Engine Brake Enable Switch
• SPN 520192

Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.