Brake Proportioning/Combination Valve: Testing and Inspection

PROPORTIONING VALVE FUNCTION TEST

CAUTION: The proportioning valves are installed independently for the right and left brake lines. Always measure each valve.





1. Connect two pressure gauges to the output port of the master cylinder and output port of the proportioning valve.
2. Bleed the brake line and the pressure gauges.





3. Depress the brake pedal gradually. Then check that the split point, where the output fluid pressure begins to drop in proportion to the output fluid pressure, is at the standard value.
Standard value: 2.69 - 3.19 MPa (390 - 463 psi)
4. Depress the brake pedal more strongly than at the above step. Then check that the output fluid pressure is at the standard value when the input fluid pressure is 6.86 MPa (995 psi).
Standard value: 3.67 - 4.17 MPa (532 - 606 psi)
5. Measure each output fluid pressure at both valves, and check that the difference between the two is at the limit value or less.
Limit: 0.5 MPa (73 psi)
6. If the measured pressure exceeds the limit, replace the proportioning valve.