Combination/Proportioning Valve

DESCRIPTION






This vehicle uses proportioning valves that are inline with the rear brake tubes. The chassis brake tubes connect directly from the master cylinder or HCU (ABS models) to the rear brake flex hose. The non ABS brake system uses two proportioning valves in-line with each of the rear wheel chassis brake tubes. Vehicles not equipped with ABS have the proportioning valves located on the front suspension crossmember in the same area as the hydraulic unit mounts on ABS equipped vehicles.






On vehicles equipped with antilock brakes, the proportioning valves are located under the vehicle on the passenger side just rearward of the passenger seat. The proportioning valves mount directly in the chassis brake tube going to each of the vehicles rear brakes.
For additional information and procedures on proportioning valves on vehicles with ABS, refer to Brakes, Antilock Braking System.






There are two proportioning valve assemblies used in each vehicle. During any service procedures identify valve assemblies by supplier part number or the bar code label and stamp identification band.

OPERATION
Proportioning valves balance front to rear braking by controlling at a given ratio, the increase in rear brake system hydraulic pressure above a preset level (split point). Under light pedal application, the proportioning valve allows full hydraulic pressure to be applied to the rear brakes.
This vehicle's brake system uses different calibrations for the proportioning valves depending on application.
For specifications on valves for particular brake applications, refer to Diagnosis And Testing.