Caravan V6-181 3.0L VIN 3 FI (1988)
Brake Proportioning/Combination Valve: Testing and Inspection
Fig. 2 Height sensing proportioning valve assembly.
Fig. 3 Master cylinder & brake warning switch.
All Mini Vans use a height sensing proportioning valve in addition to a pressure differential switch. When a premature rear wheel skid is obtained during
braking, it may be an indication that fluid pressure to rear brakes is above a desired output and/or a malfunction has occurred within the proportioning
valve. At this time, the proportioning valve unit should be tested as follows:
1.
Remove actuator assembly adjustment nut, then disconnect assembly from valve lever and remove.
2.
Install gauge and Tee from line pressure set No. C-4007 or equivalent in line with either master cylinder port to the brake valve assembly.
3.
Install second gauge from line pressure set No. C-4007 or equivalent to either rear brake outlet port between proportioning valve assembly and
rear brake line. Bleed both hydraulic circuits and the gauges.
4.
Have an assistant exert pressure on the brake pedal to get a reading on the outlet gauge. Outlet test pressure should read 100-200 psi.
5.
Inlet pressure should be 500 psi. If not, replace valve and torque mounting bolts to 250 inch lbs.
6.
If both gauges read correctly, reinstall actuator assembly, then adjust and road test vehicle.
