Hombre S Regular Cab 4WD V6-4.3L (1999)
Brake Proportioning/Combination Valve: Description and Operation
Combination Valve
Combination Valve Description
The combination valve has three sections. Each section serves a different function.
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The metering, or hold off, section limits front disc brake pressure, allowing just enough pressure to overcome the rear brake shoe springs.
When the inlet pressure is below 200 kPa (30 psi), there is no restriction. This allows for pressure equalization when the brakes are not
applied.
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The pressure differential warning switch constantly compares front and rear brake pressures from the master cylinder. The switch activates the
BRAKE warning lamp when a pressure differential occurs between the front and rear brake system. The switch latches in the warning position
after a malfunction occurs. To turn off the lamp, you must repair the malfunction and apply enough pedal pressure in order to develop about
3100 kPa (450 psi) brake line pressure.
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The proportioning section limits brake line pressure to the rear brakes after a predetermined rear input brake line pressure is reached. This
minimizes rear wheel lockup on vehicles with light rear wheel loads.
The bypass feature on the combination valve ensures full system pressure to the rear brakes when there is a malfunction in the front brake system.
