Toyota Sequoia (2005). Manual - part 274

DIDLU–01

–

DIAGNOSTICS

ABS WITH EBD & BA & TRAC & VSC SYSTEM

DI–891

1085

ABS WITH EBD & BA & TRAC & VSC SYSTEM
PRECAUTION

NOTICE:
When disconnecting the battery terminal, initialize the following system after the terminal is recon-
nected.

System Name

See Page

Back Door Power Window Control System

BE–77

When there is a malfunction in the contact point of the terminals or installation problems with
parts, removal and installation of the suspected problem parts may return the system to the
normal condition either completely or temporarily.

In order to determine the malfunctioning area, be sure to check the conditions at the time the
malfunction occurred, such as by DTC output and freeze frame data output, and record it before
disconnecting each connector or removing and installing parts.

Since the ABS with EBD & BA & TRAC & VSC systems may be influenced by a malfunction in
the other systems, be sure to check for DTCs in the other systems.

Be sure to remove and install the ABS & VSC actuator and each sensor with the IG switch OFF
unless specified in the inspection procedure.

When removing and installing the ABS & VSC actuator and each sensor, be sure to check that
the normal display is output in test mode inspection and in DTC output inspection after instal-
ling all the parts.

After replacing the yaw rate sensor and/or the ABS & VSC actuator assembly, make sure to per-
form yaw rate and deceleration sensors’ zero point calibration
(See page 

DI–897

).

The CAN communication system is used for data communication between the skid control ECU
(included in the actuator), the steering angle sensor, and the yaw rate sensor (the deceleration
sensor is included). If there is trouble in the CAN communication line, the DTC of the commu-
nication line is output.

If the DTC of the CAN communication line is output, repair the malfunction and troubleshoot
the ABS with EBD & BA & TRAC & VSC systems.

Since the CAN communication line has its own length and route, it can not be repaired tempo-
rarily with the bypass wire, etc.

DIDLV–01

F17996

Front Speed Sensor

ABS & VSC Actuator 
(w/ Skid Control ECU)

Level Warning Switch

Rear Speed Sensor

Rear Speed Sensor Rotor

Front Speed
Sensor Rotor

Parking Brake Switch

Stop Light Switch

Center Diff. Lock Switch *

1

TRAC OFF Switch *

2

Steering Angle Sensor

DLC3

Brake Inhibit Relay

Translate ECU

VSC Buzzer

Brake Booster
(Including Active Brake Booster 
Solenoid, Delta S Sensor and Boost-
er Pedal Switch)

Master Cylinder
Pressure Sensor

Front Speed Sensor Rotor

Front Speed Sensor

Yaw Rate Sensor
(Including Deceleration Sensor)

ABS Warning Light
VSC TRAC Warning light
VSC OFF Indicator Light *

1

TRAC OFF Indicator Light *

2

BRAKE Warning Light
SLIP Indicator Light

*

1

: Only for 4WD

*

2

: Only for 2WD

Center Diff. Lock
Position Switch

DI–892

–

DIAGNOSTICS

ABS WITH EBD & BA & TRAC & VSC SYSTEM

1086

LOCATION

DIDLW–01

F19153

Speed Sensor
(Each Wheel)

Stop Lamp Switch

Parking Brake Switch

Delta S Sensor

Yaw Rate
(Deceleration) Sensor

ABS & VSC Actuator

Skid Control
ECU

Combination
Meter

Translate
ECU

Steering Angle
Sensor

4WD ECU

ECM

CAN Communication System

Air Suspension ECU

(*1): CAN1 Circuit
(*2): CAN2 Circuit
(*3): Vehicle CAN Circuit

(*2)

(*3)

(*1)

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DIAGNOSTICS

ABS WITH EBD & BA & TRAC & VSC SYSTEM

DI–893

1087

SYSTEM DIAGRAM

DIDLX–01

DI–894

–

DIAGNOSTICS

ABS WITH EBD & BA & TRAC & VSC SYSTEM

1088

SYSTEM DESCRIPTION

1.

SYSTEM DESCRIPTION

HINT:

The yaw rate sensor and deceleration sensor are combined and in a single unit. This unit communi-
cates with the skid control ECU through the CAN communication system.

No changes have been made to the communication method between the VSC system and ECM. How-
ever, the communication method between the Translate ECU and ECM has been changed from serial
to CAN communication.

(a)

ABS
(Anti–lock Brake System)
The ABS helps prevent the wheels from locking when the brakes are applied firmly or when braking
on a slippery surface.

(b)

EBD
(Electronic Brake force Distribution)
The EBD control utilizes ABS, realizing proper brake force distribution between front and rear wheels
in accordance with driving conditions.
In addition, during braking while cornering, it also controls the brake forces of the right and left wheels,
helping to maintain vehicle behavior.

(c)

BA (Brake Assist)
The primary purpose of the brake assist system is to provide an auxiliary brake force to assist the driver
who cannot generate a large enough brake force during emergency braking, thus helping to maximize
the vehicle’s braking performance.

(d)

TRAC
(Traction Control)
The TRAC system helps prevent the drive wheels from slipping if the driver presses down on the accel-
erator pedal excessively when starting off or accelerating on a slippery surface.

(e)

VSC
(Vehicle Stability Control)
The VSC system helps prevent the vehicle from slipping sideways as a result of strong front wheel skid
or strong rear wheel skid during cornering.

2.

ABS with EBD & BA & TRAC & VSC OPERATION

(a)

The skid control ECU calculates vehicle stability tendency based on signals from the speed sensor,
yaw rate (deceleration) sensor and 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 wheel brake pressure by the brake actuator) should be implemented.

(b)

The SLIP indicator blinks and the VSC buzzer sounds to inform the driver that the VSC system is oper-
ating. The SLIP indicator also blinks when TRAC is operating, and the operation being performed is
displayed.

3.

FAIL SAFE FUNCTION

(a)

When a failure occurs in the ABS & BA & TRAC & VSC systems, the ABS and VSC warning lights come
on and ABS & BA & TRAC & VSC operations are prohibited. In addition to this, when there is a failure
that disables EBD operation, the brake warning light also comes on and EBD operation is prohibited.

(b)

If some control is prohibited due to a malfunction during its operation, that control will be cut off gradual-
ly not to change the stability of the vehicle suddenly.