Jeep 2007 Wrangler - Manual (Page 297)

WARNING!
Significant over or under-inflation of tires, or mixing
sizes of tires or wheels on the vehicle can lead to loss
of braking effectiveness.
The Anti-Lock Brake System conducts a low speed self-
test at about 12 mph (20 km/h). If for any reason, your
foot is on the brake when the vehicle reaches 12 mph (20
km/h), this check will be delayed until 25 mph (40
km/h).
The Anti-Lock Brake System pump motor runs during
the self-test and during an ABS stop to provide the
regulated hydraulic pressure. The motor pump makes a
low humming noise during operation, this is normal.
During off-road use, loss of traction can temporarily
defeat the system and cause the warning light to illumi-
nate. Turn the ignition OFF and ON again to restore
Anti-Lock Brake System function.
WARNING!
Pumping of the Anti-Lock Brakes will diminish their
effectiveness and may lead to an accident. Pumping
makes the stopping distance longer. Just press firmly
on your brake pedal when you need to slow down or
stop.
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