Electronic Skid Control System: Operation: Notes

During normal driving conditions, AC voltage is sent by wheel sensors to controller. When controller is not sensing an impending lock up, modulator vacuum solenoid is without ground circuit and normal brake pressure is transmitted to rear wheel cylinders. When controller senses an impending wheel lock up, an electrical signal is sent to energize solenoid and create a sealed hydraulic circuit between master cylinder and rear wheel cylinders. Modulator displacement piston moves slightly to increase rear brake line volume resulting in a decrease in pressure to rear wheel cylinders and eliminating lock up tendency. During a maximum braking stop, solenoid valve will continue to cycle, alternately supplying air or vacuum to modulator, until vehicle speed is less than five miles per hour or until brakes are released by driver.