Proportioning Valve
NOTE:
Premature rear wheel ABS cycling on a hard brake application may be caused by a defective proportioning valve. One proportioning valve is located on each rear wheel brake hydraulic circuit. Both proportioning valves must be checked to isolate defective proportioning valve.
- Road test vehicle to determine which rear wheel indicates a premature wheel skid. Raise and support vehicle. Remove suspect proportioning valve from brakeline. Perform STEP 1 in illustration. See Fig 1 .
- Remove retaining clip securing flex hose from bracket so brakelines will not be bent when installing proportioning valve with adapters back into vehicle.
- Install pressure Test Fitting Adapter (6892-2) into the inlet port and Adapter (8187-2) into the outlet port of proportioning valve. Install proportioning valve with adapters back into vehicle.
- Install Pressure Gauge (C-4007-A) into each adapter. Perform STEP 2 in illustration. See Fig 1 . Bleed air from pressure gauges. Have an assistant hold brake pedal down until pressure on inlet side of proportioning valve is 1000 psi (70 kg/cm2 ) and note pressure on outlet side of proportioning valve. Pressure on outlet side should be 600-700 psi (42-49 kg/cm2 ). Replace proportioning valve if pressure is not within specification.
- Remove test equipment. Reinstall brakelines on proportioning valve. Tighten brakeline nuts to 12.1 ft. lbs. (17 N.m). Bleed brake system. See BLEEDING BRAKE SYSTEM . Once brake system is bled, perform pressure test on remaining proportioning valve.