VSA System Description - VSA Modulator

The VSA 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, and the pump motor. The hydraulic control has three modes of ABS action; pressure intensifying, pressure retaining, and pressure reducing. Pressure intensifying mode (VSA) is a combination of the TCS, VSA, brake assist, and hill start assist control.

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

Mode	VSA NOSolenoidValve	VSA NCSolenoidValve	InletSolenoidValve	OutletSolenoidValve	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.
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 amount of intensified fluid pressure to respond to each mode through current control of VSA NO solenoid valve.