VSA System Description

VSA Control Unit Inputs and Outputs for 47P Connector

 

Terminal number Wire color Terminal
sign 
Description Measurement (Disconnect the VSA
control unit 47P connector) 
Terminal Conditions Voltage 
WHT/RED +B-P Power source for the pump motor 1-GND At all times Battery voltage 
LT BLU K-LINE Communication with the HDS ——— ——— ——— 
BLU/WHT STR-Z Detects steering angle sensor signal ——— ——— ——— 
GRN/YEL IG1 Power source for activating the system 4-GND Ignition switch
ON (II) 
Battery voltage 
BLU/ORN STR-G Ground for the steering angle sensor ——— ——— ——— 
GRN/WHT CLST-IG Power source for the sensor cluster ——— ——— ——— 
YEL/BLK STR-VCC Power source for the steering angle sensor ——— ——— ——— 
GRN/RED BFLS Detects brake fluid level switch and parking brake switch signal 9-GND Brake
fluid
level 
High Battery voltage 
Low Below 1.0 V 
11 WHT CAN1-H F-CAN
communication circuit 
——— ——— ——— 
13 BRN/YEL WL-EBD Drives brake system indicator 13-GND Brake
system
indicator 
ON Battery voltage 
OFF Below 2.2 V 
15 RED CAN1-L F-CAN
communication circuit 
——— ——— ——— 

VSA Control Unit Inputs and Outputs for 47P Connector (cont'd)

 

Terminal number Wire color Terminal
sign 
Description Measurement (Disconnect the VSA
control unit 47P connector) 
Terminal Conditions Voltage 
16 BLK GND-V Ground for the VSA modulator-control unit 16-GND At all times 0 V 
17 PNK/BLK VSA Drives VSA system indicator 17-GND VSA indicator ON 4-6 V 
OFF Below 1.0 V 
24 GRY SLD-GND CAN2
communication circuit shield 
——— ——— ——— 
25 PNK CAN2-L CAN2
communication circuit 
——— ——— ——— 
27 RED/WHT VSA OFF SW Detects VSA OFF
switch signal 
——— ——— ——— 
28 RED/YEL STR-A Detects steering angle sensor signal ——— ——— ——— 
29 WHT CAN2-H CAN2
communication circuit 
——— ——— ——— 
30 YEL/RED STR-B Detects steering angle sensor signal ——— ——— ——— 
31 LT GRN CLST-GND Ground for the sensor cluster ——— ——— ——— 
32 WHT/BLU +B-V Power source for the fail-safe relay 32-GND At all times Battery voltage 

Terminal number Wire color Terminal
sign 
Description Measurement (Disconnect the VSA
control unit 47P connector) 
Terminal Conditions Voltage 
33 BLU FR-GND Detects right-front wheel sensor signal ——— ——— ——— 
34 GRN/BLK FR +B ——— ——— ——— 
35 GRN/YEL ACT Drives VSA activation indicator 35-GND VSA
activation
indicator 
ON Below 2.4 V 
OFF Battery voltage 
36 YEL/RED RL +B Detects left-rear wheel sensor signal ——— ——— ——— 
37 GRY/RED RL-GND ——— ——— ——— 
42 BLU/YEL RR-GND Detects right-rear wheel sensor signal ——— ——— ——— 
43 GRN/YEL RR +B 
44 BLU/RED ABS Drives ABS indicator 44-GND ABS indicator ON 4-6 V 
OFF Below 1.0 V 
45 BLU/ORN FL +B Detects left-front wheel sensor signal ——— ——— ——— 
46 BRN/WHT FL-GND 
47 BLK GND-P Ground for the pump motor 47-GND At all times 0 V 

ABS Features


When the brake pedal is pressed while driving, the wheels can lock before the vehicle comes to a stop. In such an event, the maneuverability of the vehicle is reduced if the front wheels are locked, and the stability of the vehicle is reduced if the rear wheels are locked, creating an extremely unstable condition. The ABS precisely controls the slip rate of the wheels to ensure maximum grip force from the tyres, and it thereby ensures maneuverability and stability of the vehicle.
The ABS calculates the slip rate of the wheels based on the vehicle speed and the wheel speed, then it controls the brake fluid pressure to reach the target slip rate.

Grip Force of Tyre and Road Surface 


TCS Features


The TCS provides low-speed traction. When a drive wheel loses traction on a slippery road surface and starts to spin, the VSA modulator-control unit applies brake pressure to slow the spinning wheel. At that time, the VSA modulator-control unit sends a traction control signal to reduce engine power.

 

Brake Assist Function


If the brake operating force by driver is not enough in panic braking situations, it can not make the maximum braking force of the vehicles.
This function supports the driver in this case.
In this case, this function makes the bigger braking force than the brake operating force by driver.

 

Brake Assist control pattern

The VSA modulator-control unit calculates the Master Cylinder pressure gradient from the pressure sensor signal and the wheel speed for each wheel from the wheel speed sensor signal. If panic braking is detected by monitoring the Master Cylinder pressure gradient, increase all Wheel Cylinder pressure.
After the wheel cylinder pressure increased, if the VSA modulator-control unit judges slip condition from the wheel speed for each wheel and wheel acceleration, the VSA modulator-control unit decides one of the three pressure modification mode which are pressure intensifying, pressure retaining and pressure reducing according to the wheel slip status, to regulate the Wheel Cylinder pressure.

VSA System Features


Oversteer control

Applies the brake to the front and rear outside wheels

 

Understeer control (in acceleration)

 

Modulator Unit


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

ABS Control


Pressure intensifying mode

VSA NO valve open, VSA NC valve closed, inlet valve open, outlet valve closed.
Master cylinder fluid is pumped out to the caliper.

Pump motor

When starting the pressure reducing mode, the pump motor is ON. When stopping ABS operation, the pump motor is OFF.
The reservoir fluid is pumped out by the pump, through the damping chamber, to the master cylinder.

 


Pressure retaining mode

VSA NO valve open, VSA NC valve closed, inlet valve closed, outlet valve closed.
Caliper fluid is retained by the inlet valve and outlet valve.

 

Pressure reducing mode

VSA NO valve open, VSA NC valve closed, inlet valve closed, outlet valve open.
Caliper fluid flows through the outlet valve to the reservoir.

 


TCS Control


Pressure intensifying mode

VSA NO valve closed, VSA NC valve open, inlet valve open, outlet valve closed, pump motor ON.
The reservoir and master cylinder fluid is pumped out by the pump, through the damping chamber, to the front caliper.

 

Pressure retaining mode

VSA NO valve closed, VSA NC valve open, inlet valve closed, outlet valve closed, pump motor ON.
Front caliper fluid is retained by the inlet valve and outlet valve.

 



Pressure reducing mode

VSA NO valve closed, VSA NC valve open, inlet valve closed, outlet valve open, pump motor ON.
Caliper fluid flows through the outlet valve to the reservoir.

 

VSA Control


Pressure intensifying mode

VSA NO valve closed, VSA NC valve open, inlet valve open, outlet valve closed, pump motor ON.
The reservoir and master cylinder fluid is pumped out by the pump, through the damping chamber, to the front and rear calipers.

 



Pressure retaining mode

VSA NO valve closed, VSA NC valve open, inlet valve closed, outlet valve closed, pump motor ON.
Front and rear caliper fluid is retained by the inlet valve and outlet valve.

 

Pressure reducing mode

VSA NO valve closed, VSA NC valve open, inlet valve closed, outlet valve open, pump motor ON.
Caliper fluid flows through the outlet valve to the reservoir.