TOYOTA RAV4 2006 Service Repair Manual

BC–18BRAKE CONTROL – VEHICLE STABILITY CONTROL SYSTEM
BC
(3) Front Wheel Skid Tendency
When the skid control ECU determines that
there is a front wheel skid tendency, it controls
the VSC to dampen the front wheel skid. At the
same time, it effects cooperative control with the
EPS to provide steering torque assist, which
facilitates the driver's steering maneuvers to
stabilize the vehicle posture. To prevent
excessive steering maneuvers, it provides a
steering torque assist. This assist increases the
resistance to counter the driver's steering effort,
if the driver turns the steering wheel excessively.
(4) Rear Wheel Skid Tendency
When the skid control ECU determines that
there is a rear wheel skid tendency, it controls
the VSC to dampen the rear wheel skid. At the
same time, it effects cooperative control with the
EPS to provide steering torque assist, which
facilitates the driver's steering maneuvers in the
direction to correct the rear wheel skid.
(5) Acceleration During Cornering
A sudden acceleration of the vehicle during
cornering may cause a drive wheel to freewheel,
which could cause the front wheels or rear
wheels to skid. If the skid control ECU
determines that there is freewheeling of a drive
wheel, a front wheel skid tendency, or a rear
wheel skid tendency, it effects cooperative
control with the 4WD system to optimally control
the drive torque distribution to the front and rear
wheels. Furthermore, it controls the TRC and
the VSC as needed to ensure driving stability
and acceleration performance.
(b) Operation
The operation of the solenoid valves under the
cooperative control is the same as the TRC or VSC
operation.
3. ABS WITH EBD, BA, TRC 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 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 ABS
and TRACTION 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.

BRAKE CONTROL – VEHICLE STABILITY CONTROL SYSTEMBC–19
BC
4. FAIL SAFE FUNCTION
(a) When a failure occurs in the ABS with BA, TRC and
VSC systems, the ABS and VSC warning lights
illuminate, the slip indicator light comes on*1 or
remains off*2, and the operations of those systems
are 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.
HINT:
*1: for 2WD
*2: for 4WD
(b) If control is prohibited due to a malfunction during
operation, control is disabled gradually to avoid
sudden vehicle instability.
5. INITIAL CHECK
(a) When the vehicle speed first reaches approximately
6 km/h (4 mph) or more after the ignition switch is
turned ON, each solenoid valve and the motor of the
ABS and TRACTION actuator are sequentially
activated to perform electrical checks. During the
initial check, the operating sound of the solenoid
valve and motor can be heard from the engine
compartment, but this does not indicate a
malfunction.
6. SERVICE MODE
(a) VSC operation can be disabled by operating the
intelligent tester.
HINT:
Refer to the intelligent tester operator's manual for
further details.
7. FUNCTION OF COMPONENTS
Components Functions
Speed Sensor
(Semiconductor Type)Detects the wheel speed and sends the signal to skid
control ECU
Skid Control ECU
(Housed in ABS and TRACTION Actuator)• Processes the signals from each sensor to control the
ABS, BA, TRC, and VSC
• Sends and receives control signals to and from the
ECM, yaw rate and deceleration sensor, steering
sensor, etc. via CAN communication.
ABS and TRACTION 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
Solenoid Relay • Supplies power to each solenoid
• Housed in the skid control ECU
Motor Relay (VSC MTR Relay) • Supplies power to the pump motor
• Installed in engine room No. 1 relay block
Fail-safe Relay (VSC FAIL Relay) • Cuts off power to the motor when the pump motor circuit
malfunctions
• Installed in engine room No. 1 relay block

BC–20BRAKE CONTROL – VEHICLE STABILITY CONTROL SYSTEM
BC
HINT:
*1: w/ Downhill assist control
*2: for 2WD w/ AUTO LSD
Steering 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 deflection of the piezoelectric
ceramics
• Deceleration sensor measures the capacity of the
condenser that changes the distance between the
electrodes depending on G force, which occurs when
the vehicle is accelerated, and converts the measured
value into electrical signals
• Sends signals to the skid control ECU via CAN
communication
Master Cylinder Pressure Sensor • Detects the brake fluid pressure in the master cylinder
• Housed in the ABS and TRACTION actuator
ECM• Controls the engine output when TRC and VSC are
operating with the skid control ECU via CAN
communication
Downhill Assist Control switch*1 Allows the driver to turn downhill assist control ON and OFF
AUTO LSD switch*2 Allows the driver to turn AUTO LSD ON and OFF
Combination Meter 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 • Illuminates to inform the driver that a malfunction in the
VSC system has occurred
• Blinks to indicate DTCs that relate to the VSC
Brake Warning light • Illuminates to inform the driver that the parking brake is
ON when the system is normal, and when the 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 TRC, VSC, downhill
assist control and hill-start assist control are operating
• Illuminates to inform the driver that a malfunction has
occurred in the TRC or VSC system
AUTO LSD Indicator Light*2 Lights up to inform the driver when AUTO LSD operation is
possible
Downhill Assist Control Indicator
Light*1Lights up to inform the driver when downhill assist control
operation is possible
Skid Control Buzzer • Intermittently sounds to inform the driver that the VSC is
operating
• Housed in the combination meter Components Functions

BRAKE CONTROL – VEHICLE STABILITY CONTROL SYSTEMBC–21
BC
HOW TO PROCEED WITH
TROUBLESHOOTING
HINT:
• Use these procedures to troubleshoot the vehicle stability
control system.
• *: Use the intelligent tester.
NEXT
Standard voltage:
11 to 14 V
If the voltage is below 11 V, recharge or replace the battery
before proceeding.
NEXT
NEXT
Result
B
A
NEXT
(a) Use the intelligent tester to check for normal functioning
of the CAN communication system.
(1) Perform bus check (communication malfunction
DTC).
1VEHICLE BROUGHT TO WORKSHOP
2INSPECT BATTERY VOLTAGE
3CHECK AND CLEAR DTC*
4PROBLEM SYMPTOM CONFIRMATION
Result Proceed to
Symptom does not occur A
Symptom occurs B
Go to step 7
5SYMPTOM SIMULATION
6CHECK COMMUNICATION FUNCTION OF CONTROLLER AREA NETWORK (CAN)*

BC–22BRAKE CONTROL – VEHICLE STABILITY CONTROL SYSTEM
BC
Result
B
A
Result
B
A
Result
B
A
(a) Terminals of ECU (see page BC-41)
(b) Data List / Active Test (see page BC-52)
NEXT
NEXT
Result Proceed to
DTC is not output A
DTC is output B
Go to CAN COMMUNICATION SYSTEM
7CHECK FOR DTC*
Result Proceed to
DTC is not output A
DTC is output B
Go to step 10
8PROBLEM SYMPTOMS TABLE
Result Proceed to
Fault is not listed in problem symptoms table A
Fault is listed in problem symptoms table B
Go to step 10
9OVERALL ANALYSIS AND TROUBLESHOOTING
Go to step 11
10CHECK FOR FLUID LEAKAGE

BRAKE CONTROL – VEHICLE STABILITY CONTROL SYSTEMBC–23
BC
NEXT
NEXT
11REPAIR OR REPLACE
12CONFIRMATION TEST
END

BC–24BRAKE CONTROL – VEHICLE STABILITY CONTROL SYSTEM
BC
CHECK FOR INTERMITTENT
PROBLEMS
1. CHECK FOR INTERMITTENT PROBLEMS
HINT:
A momentary interruption (open circuit) in the connectors
and/or wire harness between the sensors and ECUs can
be detected by using the ECU DATA LIST function of an
intelligent tester.
(a) Turn the ignition switch OFF and connect the
intelligent tester (with CAN VIM) to the DLC3.
(b) Turn the ignition switch ON.
(c) Follow the prompts on the intelligent tester to
display the DATA LIST and select areas where a
momentary interruption should be monitored.
HINT:
• A momentary interruption (open circuit) cannot
be detected for 3 seconds after the ignition
switch is turned ON (initial check).
• If the status remains on the ERROR display,
check for continuity between the ECU and the
sensors, or between ECUs.
• The ERROR display on the intelligent tester
remains on for 1 second after the harness signal
changes from a momentary interruption (open
circuit) to normal condition.
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C122684E02
Item (Display) Measurement Item /
Range (Display)Normal Condition Diagnostic Note
FR SPD OPN FR speed sensor open detection /
ERROR or NORMALERROR: Momentary interruption
NORMAL: Normal-
FL SPD OPN FL speed sensor open detection /
ERROR or NORMALERROR: Momentary interruption
NORMAL: Normal-
RR SPD OPN RR speed sensor open detection
/ ERROR or NORMALERROR: Momentary interruption
NORMAL: Normal-
RL SPD OPN RL speed sensor open detection /
ERROR or NORMALERROR: Momentary interruption
NORMAL: Normal-
EFI COM OPN EFI communication open
detection / ERROR or NORMALERROR: Momentary interruption
NORMAL: Normal-

BRAKE CONTROL – VEHICLE STABILITY CONTROL SYSTEMBC–25
BC
(d) While observing the screen, gently jiggle the
connector or wire harness between the ECU and
sensors, or between ECUs.
OK:
ERROR display does not change.
HINT:
The connector and/or wire harness have a
momentary interruption (open circuit) if the display
changes. Repair or replace the connector and wire
harness if either of them is faulty.
YAW RATE OPN Yaw rate sensor open detection /
ERROR or NORMALERROR: Momentary interruption
NORMAL: Normal-
DECELERAT OPN Deceleration sensor open
detection / ERROR or NORMALERROR: Momentary interruption
NORMAL: Normal-
STEERING OPN Steering angle sensor open
detection / ERROR or NORMALERROR: Momentary interruption
NORMAL: Normal-
M/C OPN Master cylinder pressure sensor
open detection / ERROR or
NORMALERROR: Momentary interruption
NORMAL: Normal- Item (Display) Measurement Item /
Range (Display)Normal Condition Diagnostic Note
C122685

BC–26BRAKE CONTROL – VEHICLE STABILITY CONTROL SYSTEM
BC
CALIBRATION
1. DESCRIPTION
(a) After replacing components relating to the VSC or
performing "Front wheel alignment adjustment",
clear and read the sensor calibration data.
(b) Follow the chart to perform calibration.
2. CLEAR ZERO POINT CALIBRATION DATA (When
Using Intelligent Tester)
(a) Clear the zero point calibration data.
(1) Connect the intelligent tester (with CAN VIM) to
the DLC3.
(2) Turn the ignition switch ON.
(3) Operate the intelligent tester to erase the codes
(select "Reset Memory").
HINT:
Refer to the intelligent tester operator's manual
for further details.
(4) Using the intelligent tester, perform the zero
point calibration of the yaw rate and deceleration
sensor.
CAUTION:
If the ignition switch is turned ON for more
than 15 seconds with the shift lever in the P
position after zero point of the yaw rate and
acceleration sensor has been cleared, only
the zero point of the yaw rate sensor will be
stored. If the vehicle is driven under this
condition, the skid control ECU will
recognize that zero point calibration of the
acceleration sensor is not completed and will
indicate that there is a malfunction in the
VSC system using the indicator light.
Replacing Parts / Operation Necessary Operation
Skid Control ECU Yaw rate and deceleration sensor zero point calibration.
Yaw Rate Sensor 1. Clearing zero point calibration data
2. Yaw rate and deceleration sensor zero point calibration
Front Wheel Alignment Adjustment 1. Clearing zero point calibration data
2. Yaw rate and deceleration sensor zero point calibration
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C106531

BRAKE CONTROL – VEHICLE STABILITY CONTROL SYSTEMBC–27
BC
3. PREFORM ZERO POINT CALIBRATION OF YAW
RATE AND DECELERATION SENSOR (When Using
Intelligent Tester)
NOTICE:
• While obtaining the zero point, do not vibrate the
vehicle by tilting, moving or shaking it and keep it
stationary. (Do not start the engine.)
• Perform this on a level surface (with an inclination
of less than 1
).
(a) Procedures for Test Mode.
(1) Check that the shift lever is in the P position and
apply the parking brake.
NOTICE:
DTCs C1210/36 and C1336/39 will be
recorded if the shift lever is not the P
position (see page BC-88).
(2) Connect the intelligent tester (with CAN VIM) to
the DLC3.
(3) Turn the ignition switch ON.
(4) Set the intelligent tester to test mode (select
"Test Mode").
HINT:
Refer to the intelligent tester operator's manual
for further details.
(b) Obtain the zero point of the yaw rate and
deceleration sensor.
(1) Keep the vehicle stationary on a level surface for
2 seconds or more.
(2) Check that the VSC warning light blinks as
shown in the illustration.
HINT:
• If the VSC warning light does not blink,
perform the zero point calibration again.
• The zero point calibration is performed only
once after the system enters test mode.
• Calibration cannot be performed again until
the stored data is cleared once.
(3) Turn the ignition switch OFF.
B127989E01
C106532
C108848E14