Electra Park Avenue V6-231 3.8L VIN 3 FI (1988)
Brake Master Cylinder: Description and Operation
Master Cylinder and Main Valve Operation, ABS
The ABS master cylinder applies hydraulic pressure to the LF and RF wheel cylinders. During non-antilock braking, the master cylinder operates as
follows:
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The reservoir provides fluid under atmospheric pressure to the master cylinder piston(s).
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The booster piston force provides the master cylinder piston force to apply the LF and RF brakes. The ABS main valve allows booster hydraulic
pressure to assist in applying the front brakes during antilock braking. As part of its antilock control, the EBCM completes the main valve
solenoid circuit Figure 2-15). This causes the master cylinder to operate as follows:
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The main valve blocks the reservoir-to-master cylinder passage and opens the booster-to-master cylinder passage.
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Booster hydraulic pressure directly applies the LF and RF channels, keeping the channels full of pressurized fluid during the cycling of the inlet
and outlet valves (Figure 2-16). A driver feels the effect of main valve operation during antilock braking when the brake pedal rises slightly
against foot pressure.
