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.
The basic system is the same as that for the Lancer.

• EBD (Electronic Brake-force Distribution system)

control provides the ideal braking force for the
rear wheels.

• To shorten the harness wires and enhance data

transmission 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 ensures that safety is main-

tained.

• Diagnostic function provides improved service-

ability.

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. The front and
rear wheel slippage are calculated from the signals
received from the various wheel sensors. EBD con-
trol 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.

GENERAL DESCRIPTION

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ANTI-LOCK BRAKING SYSTEM (ABS)

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

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ANTI-LOCK BRAKING SYSTEM (ABS)

35B-4

SYSTEM CHECK SOUND

When the vehicle speed reaches 10 km/h after igni-
tion switch ON, a thudding sound can sometimes be
heard coming from the engine compartment. This is
a normal sound during the ABS self-check.

ABS OPERATION SOUNDS AND
SENSATIONS

During normal operation, the ABS makes several
sounds that may seem unusual at first:

• A whining sound is caused by the ABS hydraulic

unit motor.

• When pressure is applied to the brake pedal, the

pulsation of the pedal causes a scraping sound.

• When the brakes are applied firmly, the ABS

operates, rapidly applying and releasing the
brakes many times per second. This repeated
application and release of braking forces can
cause the suspension to make a thumping sound
and the tires to squeak.

LONG STOPPING DISTANCES ON LOOSE
ROAD SURFACES

When braking on loose surfaces like snow-covered
or gravel roads, the stopping distance can be longer
for an ABS-equipped vehicle than the stopping dis-
tance for a vehicle with a conventional brake system.

SHOCK AT STARTING CHECK

Shock may be felt when the brake pedal is lightly
pressed while driving at a low speed. This is a nor-
mal characteristic because the ABS system opera-
tion check is carried out when vehicle speed is 8
km/h (5 mph) or less.

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