Honda Civic. Manual — part 7

EBD FEATURES

The electronic brake distribution (EBD) feature helps control vehicle braking by
adjusting the rear brake force in accordance with the rear wheel load before the
ABS operates. Based on the wheel sensor signals, the control unit uses the
modulator to control the rear brakes individually. When the rear wheel speed is less
than the front wheel speed, the ABS modulator-control unit retains the current rear
brake fluid pressure by closing the inlet valve in the modulator. As the rear wheel
speed increases and approaches the front wheel speed, the ABS modulator-control
unit increases the rear brake fluid pressure by momentarily opening the inlet valve.
This whole process is repeated very rapidly. While this is happening, there is
kickback at the brake pedal.

Fig. 8: Identifying Rear Wheel Brake Pressure

MODULATOR UNIT

The ABS modulator consists of the inlet solenoid valve, the outlet solenoid valve,
the reservoir, the pump, the pump motor, and the damping chamber. The modulator
reduces the caliper fluid pressure directly. It is a circulating-type modulator because
the brake fluid circulates through the caliper, the reservoir, and the master cylinder.
The hydraulic control has three modes; pressure intensifying, pressure retaining,
and pressure reducing. The hydraulic circuit is an independent four channel type;
one channel for each wheel.

2008 Honda Civic GX

2006-08 BRAKES ABS System - Civic (All Except Hybrid)

Fig. 9: Identifying Modulator Unit Circuit Diagram

MODES AND INLET/OUTLET SOLENOID VALVE POSITION

CIRCUIT DIAGRAM

Mode

Inlet

Solenoid

Valve

Outlet

Solenoid

Valve

Brake Fluid

Pressure
intensifying
mode

open

closed

Master cylinder fluid is pumped out
to the caliper.

Pressure
retaining mode

closed

closed

Caliper fluid is retained by the inlet
and outlet valves.

Pressure
reducing mode

closed

open

Caliper fluid flows through the
outlet valve to the reservoir.

The motor pumps the reservoir
fluid through the damping
chamber to the master cylinder

(1)

.

(1)

The motor will keep running until the operation of the one anti-lock brake
control is finished with the first pressure reducing mode.

2008 Honda Civic GX

2006-08 BRAKES ABS System - Civic (All Except Hybrid)

Fig. 10: Anti-Lock Brake System Circuit Diagram (1 Of 3)

2008 Honda Civic GX

2006-08 BRAKES ABS System - Civic (All Except Hybrid)

Fig. 11: Anti-Lock Brake System Circuit Diagram (2 Of 3)

2008 Honda Civic GX

2006-08 BRAKES ABS System - Civic (All Except Hybrid)