Grand Cherokee 2WD V8-5.2L VIN Y (1998)
Brake Proportioning/Combination Valve: Description and Operation
The combination valve contains a pressure differential valve and switch and a rear brake proportioning valve. The valve is not repairable and must be
replaced as an assembly if diagnosis indicates this is necessary.
The pressure differential switch is connected to the brake warning light. The switch is actuated by movement of the switch valve. The switch monitors
fluid pressure in the separate front/rear brake hydraulic circuits.
A decrease or loss of fluid pressure in either hydraulic circuit will cause the switch valve to shuttle to the low pressure side. Movement of the valve
pushes the switch plunger upward. This action closes the switch internal contacts completing the electrical circuit to the red warning light. The switch
valve will remain in an actuated position until repairs to the brake system are made.
The proportioning valve is used to balance front-rear brake action. The valve allows normal fluid flow during moderate effort brake stops. The valve
only controls (meters) fluid flow during high effort brake stops.
