Proportioning Valve

WARNING: This page is about a different car, the 2003 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.

Connect pressure gauges to input and output ports of proportioning valve. See Fig 1 .
Bleed brake line and gauges. See BRAKE SYSTEM under BLEEDING.
Slowly depress brake pedal. Check readings on pressure gauges. Ensure output pressure begins to drop relative to input pressure at 533-604 psi (3.68-4.17 MPa).
Depress the brake pedal more strongly than at the previous step. Then check that the output fluid pressure is at 676-747 psi (4.66-5.15 MPa) when the input fluid pressure is 1138 psi (7.84 MPa).
Measure output fluid pressure of both valves, and check that the difference between both is 73 psi (0.5 MPa).
If the measured pressures exceeds the limits, replace the proportioning valve. See PROPORTIONING VALVE under REMOVAL & INSTALLATION.

Fig 1: Testing Proportioning Valves

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.