The 4ABS ensures directional stability and control
during hard braking.
This ABS uses a 4-sensor 4-channel system that
controls all four wheels independently of each other.

•

EBD (Electronic Brake-force Distribution system)
control has been added to provide the ideal brak-
ing force for the rear wheels.

•

To shorten the lines and enhance data transmis-
sion reliability, communication with other ECU is
performed over a CAN (Controller Area Network).
NOTE: For further details on CAN communica-
tion, refer to GROUP 54C, CAN.

•

Fail-safe function which ensures that safety is
maintained.

•

Diagnostic function which provides improved ser-
viceability.

EBD CONTROL

In ABS, electronic control is used so the rear wheel
brake hydraulic pressure during braking is regulated
by rear wheel control solenoid valves in accordance
with the vehicle's rate of deceleration, and the front
and rear wheel slippage which are calculated from
the signals received from the various wheel sensors.
EBD control is a control system which provides a
high level of control for both vehicle braking force
and vehicle stability. The system has the following
features:

•

Because the system provides the optimum rear
wheel braking force regardless of vehicle load
and the condition of the road surface, the system
reduces the required pedal depression force, par-
ticularly when the vehicle is heavily loaded.

•

Because the duty placed on the front brakes is
reduced, the increases in pad temperature can
be controlled during front brake application to
improve pad wear.

•

Control valves such as the proportioning valve
are not required.

SPECIFICATIONS

ITEM

SPECIFICATION

ABS control method

4-sensor, 4-channel

No. of wheel speed rotor
teeth

Front

Rear

Wheel speed sensor

Type

Magnet coil type

Gap between sensor and rotor mm (in)

0.2

−

0.5 (0.008

−

0.020)

<Non-adjustable type>

GENERAL DESCRIPTION

FOUR-WHEEL ANTI-LOCK BRAKE SYSTEM (4ABS)

35B-3

CONSTRUCTION DIAGRAM

AC306051

3, 7

VEHICLES FOR CANADA

VEHICLES FOR USA

NAME OF PART

NUMBER

OUTLINE OF FUNCTION

Sensor

Wheel speed sensor

Sends alternating current signals at frequencies which are
proportional to the rotation speeds of each wheel to the
ABS-ECU.

Stoplight switch

Sends a signal to the ABS-ECU to indicate whether the
brake pedal is depressed or not.

Actuator Hydraulic unit

Drives the solenoid valves according to signals from the
ABS-ECU in order to control the brake hydraulic pressure
for each wheel.

ABS warning light

Illuminates in response to signals from the ABS-ECU
when a problem develops in the ABS system.

Brake warning light

Illuminates in response to signals from the ABS-ECU
when a problem develops in the EBD system.

Data link connector

Outputs the diagnostic trouble codes and allows
communication with the scan tool.

ABS-ECU

Controls actuators (described above) based on the signals
coming from each sensor.
Controls the self-diagnosis and fail-safe functions.
Controls the diagnostic function (scan tool compatible).

GENERAL DESCRIPTION

FOUR-WHEEL ANTI-LOCK BRAKE SYSTEM (4ABS)

35B-4

SYSTEM CONFIGURATION DIAGRAM

AC305441AB

WHEEL SPEED SENSOR (FL)

FR SOLENOID VALVE (OUT)

FR SOLENOID VALVE (IN)

FL SOLENOID VALVE (OUT)

FL SOLENOID VALVE (IN)

RR SOLENOID VALVE (OUT)

RR SOLENOID VALVE (IN)

RL SOLENOID VALVE (OUT)

RL SOLENOID VALVE (IN)

STOPLIGHT SWITCH

ECU POWER SUPPLY

ABS-ECU

COMBINATION METER
(ABS WARNING LIGHT
BRAKE WARNING LIGHT)

DATA LINK
CONNECTOR

WHEEL SPEED SENSOR (RL)

WHEEL SPEED SENSOR (RR)

WHEEL SPEED SENSOR (FR)

STOPLIGHT
SWITCH

REAR-RIGHT
WHEEL (RR)

WHEEL
SPEED
SENSOR

FRONT-RIGHT
WHEEL (FR)

WHEEL
SPEED
SENSOR

HYDRAULIC
UNIT

FRONT-LEFT
WHEEL (FL)

REAR-LEFT
WHEEL (RL)

WHEEL
SPEED
SENSOR

CAN-BUS LINE

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