Test for faulty proportioning valve:
Drive the vehicle and have an assistant
observe during the performance of this test.
With vehicle at curb weight, decelerate vehicle
(S/N 299999 AND BELOW)
from 45 to 40 mph (72 to 69 kph) on dry
concrete road and apply sufficient pressure to
lock up front brakes. If rear brakes lock up
before front brakes, the proportioning valve
should be replaced.
Replace proportioning valve
(S/N 300000 AND ABOVE)
Method for checking hydro-booster:
Depress brake pedal several items to
exhaust accumulator pedal. Depress brake
pedal and start engine. Brake pedal should
fall, then push back against operator's foot.
Replace hydro-booster (TM 9-2320-387-24-1).
Replace service brake pedal
The steering tests will check for suspension
problems that will affect braking.