2001 TOYOTA HIGHLANDER 4WD

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TOYOTA HIGHLANDER 2001 Service Repair Manual 2005 HIGHLANDER (EWD592U)
184
VSC and Tire Pressure Warning System
1. ABS Operation
If the brake pedal is depressed suddenly, the ABS controls the hydraulic pressure of the wheel cylinders for all the

2005 HIGHLANDER (EWD592U)
184
VSC and Tire Pressure Warning System
1. ABS Operation
If the brake pedal is depressed suddenly, the ABS controls the hydraulic pressure of the wheel cylinders for all the four
wheels to automatically avoid wheel locking and ensure the directional and steering stability of the vehicle. If the brake pedal
is depressed suddenly, the skid control ECU with actuator controls the solenoids in the actuators using the signals from the
sensors to move the brake fluid to the reservoir in order to release the braking pressure applied to the wheel cylinder. If the
skid control ECU with actuator detects that the fluid pressure in the wheel cylinder is insufficient, the ECU controls the
solenoids in the actuators to increase the braking pressure.
2. Traction Control Operation
The traction control system controls the engine torque, the hydraulic pressure of the driving wheel cylinders, slipping of the
wheels which may occur at start or acceleration of the vehicle, to ensure an optimal driving power and vehicle stability
corresponding to the road conditions.
3. VSC Operation
Unexpected road conditions, vehicle speed, emergency situation, and any other external factors may cause large under- or
over-steering of the vehicle. If this occurs, the VSC system automatically controls the engine power and wheel brakes to
reduce the under- or over-steering.
To reduce large over-steering :
If the VSC system determines that the over-steering is large, it activates the brakes for the outer front turning wheels
depending on the degree of the over-steering to produce the moment toward the outside of the vehicle and reduce the
over-steering.
To reduce large under-steering :
If the VSC system determines that the under-steering is large, it controls the engine power and activates the rear wheel
brakes to reduce the under-steering.
VSC indicator light
If an mulfunction occurs in the VSC system, the VSC indicator lights up to warn the driver.
4. Mutual System Control
To efficiently operate the VSC system at its optimal level, the VSC system and other control systems are mutually controlled
while the VSC system is being operated.
Engine control
The engine power does not interfere with the VSC brake control by fuel cut controlling and reducing the engine output.
Engine control and electronically controlled transmission control
The strong braking force does not interfere with the braking force control of the VSC system by turning off the accel and
reducing changes in the driving torque at shift-down.
VSC system operation indication
The slip indicator light flashes and the buzzer alarm intermittently to warn the driver that the current road is slippery, while the
VSC system is being operated.
5. Fail Safe Function
If an mulfunction occurs in the skid control ECU with actuator, sensor signals, and/or actuators, the skid control ECU with
actuator inhibits the brake actuator control and inputs the mulfunction signal to the engine control module. According to the
mulfunction signal, the brake actuator turns off the solenoid and the engine control module rejects any electronically
controlled request from the VSC system. As a result, the vehicle functions without the ABS, BA, TRAC, and VSC systems.
A4, A5 ABS Speed Sensor Front LH, RH
1-2 : 1.4-1.8 kW (20°C, 68°F)
A24, A25 ABS Speed Sensor Rear LH, RH
1-2 : 0.9-1.3 kW (25°C, 77°F) (4WD)
1-2 : Max. 1.45 kW (25°C, 77°F) (2WD)
B4 Brake Warning SW
1-2 : Closed with the float down
S27 Skid Control ECU with Actuator
46-Ground : Approx. 12 volts with the ignition SW at ON position
27-Ground : Approx. 12 volts with the stop light SW on (Brake pedal depressed)
31-Ground : Always continuity
S15 Stop Light SW
2-1 : Closed with brake pedal depressed
System Outline
Service Hints