Honda Civic. Manual — part 1080

learns the current driver's normal braking characteristics by monitoring the brake
pressure sensor and the brake pedal position switch at each stop. Using these inputs
and their values, the VSA modulator-control unit is able to learn the driver's normal
braking habits, and then determine the difference between a normal stop and a panic
stop for the individual driver of the vehicle. If during a panic stop the VSA
modulator-control unit determines that the brake system pressure increases above a
learned threshold in less than a learned amount of time, the VSA modulator-control
unit engages brake assist. Because the brake system pressure crossed the threshold
before the time threshold had expired, the VSA modulator-control unit goes into
brake assist mode.

Fig. 12: Identifying Brake Assist Features

Modulator Unit

The modulator unit consists of the inlet solenoid valve, the outlet solenoid valve,
the VSA NO (normally open) solenoid valve, the VSA NC (normally closed)
solenoid valve, the reservoir, the pump, the pump motor, and the damping chamber.

The hydraulic control has three modes at ABS action; pressure intensifying,
pressure retaining, and pressure reducing.

And pressure adding mode is combined at TCS, VSA, and brake assist action.

The hydraulic circuit is an independent four channel type; one channel for each
wheel.

2008 Honda Civic GX

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

Fig. 13: Identifying Modulator Unit Diagram

VALVE REFERENCE

Mode

VSA

NO

Valve

VSA

NC

Valve

Inlet

Solenoid

Valve

Outlet

Solenoid

Valve

Brake Fluid

Pressure
intensifying
mode

open

closed

open

closed

Master cylinder fluid is
pumped out to the
caliper.

Pressure
retaining
mode

open

closed

closed

closed

Caliper fluid is retained
by the inlet and outlet
valves.

Pressure
reducing
mode

open

closed

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)

.

2008 Honda Civic GX

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

CIRCUIT DIAGRAM

Pressure
adding mode

closed

open

open

closed

Master cylinder
fluid is pumped out
by pump with motor
through VSA NC
valve to the caliper.

Caliper fluid
pressure exceed
master cylinder
pressure.

(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 VSA System - Civic (All Except Hybrid)

Fig. 14: Identifying VSA System Circuit Diagram (1 Of 3)

2008 Honda Civic GX

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