RAM 1500 Van V8-5.2L VIN Y (1999)
Brake Proportioning/Combination Valve: Description and Operation
Combination Valve
The combination valve captains a pressure differential valve and switch, metering valve and a proportioning valve on 1500 models. The combination
valve/rear brake proportioning valve are not repairable and must be replaced as an assembly.
PRESSURE DIFFERENTIAL SWITCH
The pressure differential switch is connected to the brake warning lamp. The switch is triggered by movement of the switch valve. The purpose of the
switch is to monitor 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 forward or rearward in response to the pressure
differential. Movement of the switch valve will push the switch plunger upward. This closes the switch internal contacts completing the electrical
circuit to the warning lamp. The switch valve may remain in an actuated position until repair restores system pressures to normal levels.
METERING VALVE
Metering valve operation can be checked visually with the aid of a helper. Observe the metering valve stem while a helper applies and releases the
brakes. If the valve is operating correctly, the stem will extend slightly when the brakes are applied and retract when the brakes are released. If the
valve is faulty, replace the entire combination valve as an assembly.
