1996 Honda Civic Owner's Manual - Page 204

Anti-lock Brake System Only on cars equipped with ABS The ABS works by measuring how fast the wheels are turning during braking and comparing their speeds. If any wheel is rotating much slower than the others (on the verge of locking up and skidding), the system reduces hydraulic pressure to that wheel's brake. When (hat wheel's speed matches the other wheels, the system applies normal hydraulic pressure. This can take place several times per second at each wheel. You feel the ABS working as rapid pulsations in the brake pedal. Each wheel has a wheel speed sensor assembly. As the wheel rotates, the sensor sends electrical pulses to the ABS control unit. The pulse frequency varies with the wheel speed. The electrical output of the ABS control unit is connected to the modulator/solenoid unit. While driving, the ABS control unit monitors the pulse frequencies from the four wheels. When the control unit detects a wheel locking up, it energizes the solenoids in the modulator unit for that wheel. The system has eight solenoids which work in pairs. The energized solenoids effectively increase the chamber volume of the brake line, thereby reducing hydraulic pressure to that wheel's brake. When that wheel speeds up because of the reduced braking effort, the control unit de-energizes the solenoids. Hydraulic pressure increases in the brake line to that wheel. The control unit also contains error detection circuitry. It monitors the operation of the wheel sensors, solenoids, pump motor, and electronics. If the control unit detects any faults, it shuts off power to the pump motor and solenoids, disabling the ABS. The indicator on the instrument panel comes on. The brakes then work like a conventional system without anti-lock capabilities. Technical Information