## VSA System Description

### VSA Control Unit Inputs and Outputs for 46P Connector

Terminal number | Wire color | Terminal sign | Description | Measurement (Disconnect the VSA control unit 46P connector)
--- | --- | --- | --- | ---
Terminal | Conditions | Voltage
2 | RED/ YEL | ST-A | Detects steering angle sensor signal | 2-GND | Ignition switch ON (II) Turn steering wheel very slowly | About 1-4 V alternately
4 | BLU/ RED | WALP | Drives ABS indicator | 4-GND | Ignition switch ON (II) | Battery voltage
6 | WHT/ BLK | STOP | Detects brake switch signal | 6-GND | ——— | ———
8 | BLU/ YEL | RR-GND | Detects right-rear wheel sensor signal | ——— | ——— | ———
9 | PNK/ BLK | VSA WL | Drives VSA indicator | 9-GND | Ignition switch ON (II) | Battery voltage
10 | GRY/ RED | RL-GND | Detects left-rear wheel sensor signal | ——— | ——— | ———
11 | YEL/ RED | RL +B | Detects left-rear wheel sensor signal positive | ——— | ——— | ———
13 | BRN/ WHT | FL-GND | Detects left-front wheel sensor signal | ——— | ——— | ———
14 | BLU | OFF SW | Detects VSA off switch signal | 14-GND | Ignition switch ON (II) | Press button | Battery voltage
Released button | 0 V
15 | RED/ WHT | K-LINE | Communications with HDS | ——— | ——— | ———
16 | BRN/ YEL | EBD | Drives brake system indicator | 16-GND | Ignition switch ON (II) | Battery voltage
25 | YEL/ RED | ST-B | Detects steering angle sensor signal | ——— | ——— | ———
26 | BLU/ WHT | ST-Z | Detects steering angle sensor signal | ——— | ——— | ———
27 | GRN/ RED | PARK | Detects parking brake signal | 27-GND | Ignition switch ON (II) | Lever pull | 0 V
Lever released | Battery voltage
28 | BLU | FR-GND | Detects right-front wheel sensor signal | ——— | ——— | ———

Terminal number | Wire color | Terminal sign | Description | Measurement (Disconnect the VSA control unit 46P connector)
--- | --- | --- | --- | ---
Terminal | Conditions | Voltage
29 | GRN/ BLK | FR +B | Detects right-front wheel sensor signal positive | ——— | ——— | ———
30 | GRN/ YEL | RR +B | Detects right-rear wheel sensor signal positive | ——— | ——— | ———
33 | YEL/ BLK | SVCC | Power source for the sensors | ——— | ——— | ———
34 | BLU/ ORN | FL +B | Detects left-front wheel sensor signal positive | ——— | ——— | ———
35 | ORN | SGND | Ground for the sensors | ——— | ——— | ———
37 | GRN/ YEL | ACT LMP | Drives information indicator | 37-GND | Ignition switch ON (II) | Battery voltage
38 | RED | CAN-L | F-CAN communication circuit | ——— | ——— | ———
39 | WHT | CAN-H | F-CAN communication circuit | ——— | ——— | ———
40 | YEL | IG1 | Power source for activating the system | 40-GND | Ignition switch ON (II) | Battery voltage
43 | BLK | GND2 | Ground for the VSA-modulator control unit | ——— | ——— | ———
44 | WHT/ GRN | +B FSR | Power source for the fail-safe relay | 44-GND | At all time | Battery voltage
45 | WHT/ RED | MR +B | Power source for the motor relay | 45-GND | At all time | Battery voltage
46 | BLK | GND1 | Ground for the pump motor | ——— | ——— | ———

#### 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 slipperly road surface and starts to spin, the VSA control unit sends a brake signal to the modulator unit, which applies brake pressure to slow the spinning wheel. At that time, the VSA control unit sends a traction control signal to reduce engine power.

### VSA System Features

#### Oversteer control

- Applies the brake to the front outside tyre

#### Understeer control (in acceleration)

- Applies the brake to the front inside tyre
- Cuts the engine torque by controlling

### 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, though 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 open, 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, front inlet valve closed, front 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.