Toyota Tundra. Manual — part 912

system is operating.

The VSC OFF indicator light blinks and the SLIP indicator light comes on to indicate a
malfunction in the AUTO LSD system.

When the vehicle is in normal mode and the VSC OFF switch is pressed for 3 seconds or
more, AUTO LSD operation becomes possible. During AUTO LSD mode, the combination
meter's AUTO LSD indicator light and SLIP indicator light illuminate, and TRAC operation
is disabled.

When the vehicle speed is more than 50 km/h (31 mph), the vehicle automatically returns to
normal mode. When the vehicle speed is 50 km/h (31 mph) or less, the vehicle returns to
AUTO LSD mode.

2. ABS with EBD, BA, TRAC and VSC OPERATION

a. The skid control ECU calculates vehicle stability tendency based on the signals from the 4 wheel

speed sensors, the yaw rate and deceleration sensor and the steering angle sensor. In addition, it
evaluates the results of the calculations to determine whether any control actions (control of the
engine output torque by electronic throttle control and of the brake fluid pressure by the VSC
actuator) should be implemented.

b. The SLIP indicator blinks and the skid control buzzer sounds to inform the driver that the VSC

system is operating. The SLIP indicator also blinks when traction control is operating, and the
operation being performed is displayed.

3. FAIL-SAFE FUNCTION

a. When a failure occurs in the ABS with BA, TRAC and VSC systems, the ABS warning light comes

on and/or the VSC OFF indicator lights blinks and the SLIP indicator light comes on, and the
operation of those systems is prohibited. In addition to this, when a failure which disables the EBD
operation occurs, the brake warning light comes on and its operation is prohibited.

b. If control is prohibited due to a malfunction during operation, control is disabled gradually to avoid

sudden vehicle instability.

4. INITIAL CHECK

a. When the vehicle speed first reaches approximately 23 km/h (14 mph) or more after the ignition

switch is turned ON, each solenoid valve and the motor of the VSC actuator are sequentially
activated to perform electrical checks. During the initial check, the operating sound of the motor
can be heard from the engine compartment, but this does not indicate a malfunction.

5. FUNCTION OF COMPONENTS

FUNCTION OF COMPONENTS

Components

Functions

Front speed sensor (Semiconductor speed sensor,

magnetic sensor rotor)



Detects the wheel speed and sends a signal to
the skid control ECU.



The magnetic sensor rotor is equipped with
north and south poles (48 poles each), which
are evenly spaced around its circumference.

2009 Toyota Tundra

2009 BRAKES Brake Control - Tundra



The magnetic field changes as the magnetic
sensor rotor rotates. The semiconductor speed
sensor detects the change and outputs it as the
vehicle speed pulse.

Rear control sensor (Semiconductor speed sensor,

magnetic sensor rotor)



The skid control sensor (semiconductor speed
sensor) and the sensor rotor (magnetic sensor
rotor) are installed on the rear axle carrier.



The skid control sensor has the same structure
and functions as the front speed sensor.

Skid control ECU (Housed in VSC actuator)



Processes the signals from each sensor to
control the ABS, BA, TRAC, and VSC.



Sends and receives control signals to and from
the ECM, yaw rate and deceleration sensor,
steering angle sensor, etc. via CAN
communication.

VSC actuator



Consists of the master cylinder cut solenoid
valve, holding solenoid valve, pressure
reduction solenoid valve, pump motor, and
reservoir, and adjusts the brake fluid pressure
applied to each wheel cylinder.



Houses the skid control ECU.

Motor relay



Supplies power source to the pump motor.



Housed in the skid control ECU.

Solenoid relay



Supplies power to each solenoid.



Housed in the skid control ECU.

Steering angle sensor



Detects the steering extent and direction and
sends signals to the skid control ECU via
CAN communication.



Has a magnetic resistance element which
detects the rotation of the magnet housed in
the detection gear in order to detect the
changes in magnetic resistance and the
steering amount and direction.

Yaw rate and deceleration sensor



Yaw rate sensor detects the vehicle's angular
velocity (yaw rate) in the vertical direction
based on the extent and direction of the quartz
tuning fork due to the Coriolis force.



Deceleration sensor measures the capacity of
the condenser that changes with the distance
between the electrodes depending on G force,
which occurs when the vehicle is accelerated,
and converts the measured value into
electrical signals.

2009 Toyota Tundra

2009 BRAKES Brake Control - Tundra

HOW TO PROCEED WITH TROUBLESHOOTING

HINT:



Sends signals to the skid control ECU via
CAN communication.

Master cylinder brake fluid pressure sensor



Detects the brake fluid pressure in the master
cylinder.



Housed in the VSC actuator.

ECM

Controls the engine output when TRAC and VSC
are operating with the skid control ECU via CAN
communication.

VSC OFF indicator light



Blinks to inform the driver that a malfunction
in the VSC system has occurred.



Blinks to indicate DTCs that relate to the
VSC.

VSC OFF switch

For 2WD vehicles or 4WD vehicles in 2H mode:
Operation of the VSC OFF switch changes the
vehicle from normal mode to TRAC OFF mode to
AUTO LSD mode to VSC OFF mode.
For 4WD vehicles in 4H or 4L mode: Operation of
the VSC OFF switch changes the vehicle from
normal mode to VSC OFF mode.

ABS warning light



Illuminates to inform the driver that a
malfunction in the ABS has occurred.



Blinks to indicate DTCs that relate to the
ABS. (VSC warning light and SLIP indicator
light illuminate at same time.)

BRAKE warning light



Illuminates to inform the driver that the
parking brake is ON when the system is
normal, and when the amount of brake fluid
has decreased.



Illuminates to inform the driver that a
malfunction in the EBD has occurred.

SLIP indicator light



Blinks to inform the driver that TRAC, VSC
or AUTO LSD is operating.



Illuminates to inform the driver that a
malfunction has occurred in the TRAC or
VSC system.

Skid control buzzer

Intermittently sounds to inform the driver that the
VSC is operating.

Stop light control relay (BRK NO. 1 and BRK NO.

2)

Controls stop light illumination according to the
signal from the skid control ECU.

2009 Toyota Tundra

2009 BRAKES Brake Control - Tundra

*: Use the Techstream.

1. VEHICLE BROUGHT TO WORKSHOP

2. INSPECT BATTERY VOLTAGE

Standard voltage: 11 to 14 V

If the voltage is below 11V, recharge or replace the battery before proceeding.

3. INSPECT COMMUNICATION FUNCTION OF CAN COMMUNICATION SYSTEM*

a. Using the Techstream, inspect the CAN communication function to ensure there are no

malfunctions in the communication system.

Result

RESULT TABLE

The skid control ECU sends the signals of each warning light to CAN communication.

B: GO TO CAN COMMUNICATION SYSTEM (See HOW TO PROCEED WITH
TROUBLESHOOTING )

A: Go to next step

4. CHECK DTC AND FREEZE FRAME DATA*

5. CLEAR DTC AND FREEZE FRAME DATA*

6. PROBLEM SYMPTOM CONFIRMATION

7. DTC CHECK AND CLEAR*

8. PROBLEM SYMPTOM CONFIRMATION

Result

RESULT TABLE

B: GO TO STEP 11

A: Go to next step

Result

Proceed to

DTC is not output

A

DTC is output

B

Result

Proceed to

Symptom does not occur

A

Symptom occurs

B

2009 Toyota Tundra

2009 BRAKES Brake Control - Tundra