What are some symptoms of a faulty proportioning valve?

Since the proportioning valve decreases the pressure sent to the rear brakes, the main symptom the valve is going bad is the rear wheels locking up when the brakes are applied. Furthermore, the wheels will lock up more easily on wet surfaces. The rear brakes may feel touchy when applied even gently.

Does the proportioning valve controls pressure to the front brakes?

The proportioning valve reduces the pressure to the rear brakes. Whichever type of brakes your vehicle has, the rear brakes require less pressure than the front brakes. If equal braking force were applied to all four wheels during a stop, the rear wheels would lock-up before the front wheels.

How do you unblock a brake proportioning valve?

Bleed the front brake lines on the proportioning valve in the same fashion. This reversal of pressure will eventually break the spool loose inside the proportioning valve, equalizing the pressure between the front and rear brakes. The dash light will go off.

Where is the proportioning valve located?

The proportioning valve part of the combination valve is located in the rear brake portion of the valve. This part of the valve probably causes the most confusion within a combination valve and is probably the most misunderstood part of a brake system.

Can a bad proportioning valve cause front brakes to lock up?

Hydraulic System A collapsed brake hose trapping fluid in the caliper will behave the same as a binding caliper. A bad brake system proportional valve delivering equal fluid pressure to the entire brake system can cause the rear wheels to lock-up during heavy braking.

Does a 4 wheel disc need a proportioning valve?

If I add disc brakes will I need a proportioning valve? Yes. The addition of a proportioning valve is a must. Without it your braking system will not operate properly.

Can you bleed a proportioning valve?

To keep the valve from misaligning, simply replace the switch with the proportioning valve centering tool (bleeder tool) prior to the brake-bleeding process. This tool prevents the valve from moving. Once the brakes have been bled, simply replace the bleeder tool with the pressure differential switch.

Do you need to bleed a proportioning valve?

How do you test a proportioning valve?

Pressure gauges are the best way to diagnose a failed proportioning valve. There will be a gage installed into the front and rear hydraulic circuits. Start the vehicle, and apply the brake pedal with heavy pedal pressure to duplicate a panic braking situation. The front and rear pressures should be different.