RAM 1500 Truck 2WD V6-3.7L VIN K (2003)
Brake Proportioning/Combination Valve: Description and Operation
DESCRIPTION - ELECTRONIC VARIABLE BRAKE PROPORTIONING
Vehicles equipped with ABS use Electronic Variable Brake Proportioning (EVBP) to balance front-to-rear braking. The EVBP is used in place of a
rear proportioning valve. The EVBP system uses the ABS system to control the slip of the rear wheels in partial braking range. The braking force of
the rear wheels is controlled electronically by using the inlet and outlet valves located in the Integrated Control Unit (ICU).
OPERATION - ELECTRONIC VARIABLE BRAKE PROPORTIONING
EVBP is able to decrease, hold and increase rear brake pressure without activating full ABS control. Upon entry into EVBP the inlet valve for the rear
brake circuit is switched on so that the fluid supply from the master cylinder is shut off. In order to decrease the rear brake pressure, the outlet valve
for the rear brake circuit is pulsed. This allows fluid to enter the Low Pressure Accumulator (LPA) in the Hydraulic Control Unit (HCU) resulting in a
drop in fluid pressure to the rear brakes. In order to increase the rear brake pressure, the outlet valve is switched off and the inlet valve is pulsed. This
increases the pressure to the rear brakes.
The EVBP will remain functional during many ABS fault modes. If both the red BRAKE and amber ABS warning indicators are illuminated, the
EVBP may not be functioning.
