VSA System Description - Components

Components

The VSA system consists of the following primary components:

VSA modulator-control unit
Wheel speed sensors
VSA OFF switch
Hill descent control switch
System indicator

For locations of each component on the vehicle, refer to the Component Location Index , and for functions of the indicator, refer to How to Troubleshoot the VSA system .

VSA Modulator

The VSA modulator unit consists of the inlet solenoid valve, outlet solenoid valve, VSA NO (normally open) solenoid valve, VSA NC (normally closed) solenoid valve, reservoir, pump, pressure sensor, and pump motor. The hydraulic control has four modes: pressure intensifying, pressure retaining, pressure reducing, and pressure intensifying mode (VSA).

Courtesy of HONDA, U.S.A., INC.

Mode	VSA NO Solenoid Valve	VSA NC Solenoid 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.

Mode	VSA NO Solenoid Valve	VSA NC Solenoid Valve	Inlet Solenoid Valve	Outlet Solenoid Valve	Brake Fluid
Pressure retaining mode	open	closed	closed	closed	Caliper fluid is retained by the inlet and outlet solenoid valves.
Pressure reducing mode	open	closed	closed	open	Caliper fluid flows through the outlet solenoid valve to the reservoir.
Pressure intensifying mode (VSA)	closed (current control)	open	open	closed	Master cylinder fluid is pumped out by the pump through the VSA NC solenoid valve to the caliper. Caliper fluid pressure exceeds master cylinder pressure. The VSA modulator unit controls the amount of intensified fluid pressure to respond to each mode through current control of VSA NO solenoid valve.

Wheel Speed Sensor

The VSA system uses four wheel speed sensors to monitor individual wheel speed. The wheel speed sensor is comprised of a semiconductor and Hall effect sensor. The speed sensor detects the magnetic field of a magnetic encoder installed on the inner sealing surface of each hub and wheel bearing assembly. The frequency of the sensor output signal is proportional to the speed of the wheel, and this signal information is sent to the VSA control unit.Also the VSA control unit detects the wheel rotation direction from the sensor output signal and sends this information to other systems via F-CAN.

Courtesy of HONDA, U.S.A., INC.