(1) Disconnect vent hose at front brake air
(2) Blow compressed air through vent hose.
(3) Check for air escaping at vent.
(4) Attach vent hose at front brake air chamber.
(5) Raise front axle off maintenance trestles.
(6) Remove maintenance trestles and lower front
wheels to ground.
(1) If rear brakes locked up before front brakes
on road test of unloaded vehicle, check load
sensing valve hardware, arm position,
adjusting clamp, and cable.
(2) If valve arm is in full up position (valve
spring rest position), adjust or replace load
sensing valve (para 11-10).