VSA System Description (VSA)

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
1	WHT	+B-FSR	Power source for the fail-safe relay	1- GND	At all times				Battery voltage
2	YEL/ RED	RL+B	Detects left-rear wheel sensor signal	2-3	Wheel	Spin wheel at 1 turn/second			AC: 0.053 V or above (Reference) Oscilloscope 0.15 V peak-to-peak or above
3	RED	RL-GND
4	BLU/ WHT	FL+B	Detects left-front wheel sensor signal	4-20
5	GRN/ YEL	RR+B	Detects rear-right wheel sensor signal	5-6
6	BLU/ YEL	RR-GND				Stopped			0.25 V-1.15 V
11	BLU	DIAG-K	Communications with Honda PGM Tester or HDS	———	———				———
14	WHT	CAN-H	F-CAN communication circuit	———	———				———
16	WHT/ RED	+B-MR	Power souce for the motor relay	16-GND	At all times				Battery votage

Terminal number	Wire color	Terminal sign	Description	Measurement (Disconnect the VSA cotrol unit 47P connector)
				Terminal	Conditions				Voltage
17	PNK	FR-GND	Detects right-front wheel sensor signal	17-18	Wheel	Spin wheel at 1 turn/second			AC: 0.053 V or above (Reference) Oscilloscope 0.15 V peak-to-peak or above
18	GRN/ BLK	FR+B
20	BRN/ WHT	FL-GND	Detects left-front wheel sensor signal	4-20
						Stopped			0.25 V-1.15 V
28	BLU	STR-A	Detects steering angle sensor signal	———	———				———
29	BLU/ ORN	STR-D	Detects steering angle sensor signal	———	———				———
30	RED	CAN-L	F-CAN communication circuit	———	———				———

Terminal number	Wire color	Terminal sign	Description	Measurement (Disconnect the VSA cotrol unit 47P connector)
				Terminal	Conditions				Voltage
32	BLK	GND	Ground for the VSA modurator-control unit	———	———				———
33	GRY/ WHT	SGND	Ground for the sensors	———	———				———
34	LT GRN	YAW	Detects YAW rate sensor signal	———	———				———
35	ORN	SVCC	Power source for the sensors	———	———				———
37	GRN	GLAT	Detects lateral acceleration sensor signal	———	———				———
38	BLK/ RED	IG1	Power source for activating the system	38-GND	Ignition swich ON (II)				Battery voltage
43	BUL/ YEL	STR-B	Detects steering angle sensor signal	———	———				———
47	BLK	MR-GND	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 the sub throttle
  

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.