2008 MITSUBISHI LANCER EVOLUTION X Workshop Manual

CONSTRUCTION DESCRIPTION
BASIC BRAKE SYSTEM35A-10
BRAKE LINEM2350005000266
PROPORTIONING VALVE
A proportioning valve is used to prevent early locking
of the rear wheels, in order to provide improved sta
-
bility during braking.
AC609305
From master cylinder rear brake system
To rear brakeO-ring U-packing Sleeve
Guide Seal
Proportioning valveMaster cylinder
SpringPlateValve
AB

35B-1
GROUP 35B
FOUR-WHEEL
ANTI-LOCK BRAKE
SYSTEM (4ABS)
CONTENTS
GENERAL INFORMATION . . . . . . . .35B-2
CONSTRUCTION DESCRIPTION . . .35B-6
SENSOR . . . . . . . . . . . . . . . . . . . . . . . . . . . 35B-6
ACTUATORS . . . . . . . . . . . . . . . . . . . . . . . 35B-6
ABS-ECU. . . . . . . . . . . . . . . . . . . . . . . . . . . 35B-7

GENERAL INFORMATION
FOUR-WHEEL ANTI-LOCK BRAKE SYSTEM (4ABS)35B-2
GENERAL INFORMATIONM2351000100830
The ABS that ensures directional stability and con-
trollability during hard braking. ABS is standard
equippment on the ES and GTS models but is
optional.
This ABS uses a 4-sensor system that controls all
four wheels independently of each other, and has the
following features:
•EBD *1 (Electronic Brake-force Distribution sys-
tem) control that can obtain ideal rear wheel
brake force has been employed.
•The magnetic encoder for detecting the wheel
speed has been installed instead of the rotor as
the wheel speed sensor.
•For wiring harness saving and secure data com-
munication, CAN *2 bus has been adopted as a
tool of communication with other ECUs.
NOTE: .
•*1: EBD (Electronic Brake-force Distribution)
•*2: For more information about CAN (Controller
Area Network), refer to GROUP 54C
P.54C-2.
.
SPECIFICATIONS
.
CONSTRUCTION DIAGRAM
.
ItemSpecifications
ABS control type4 sensors
Wheel speed sensorMagnetic encoderFront86 (N pole: 43, S pole: 43)
Rear86 (N pole: 43, S pole: 43)
Ty p eSemiconductor
AC608518
CHECK
SERVICE
REQUIRED
AB
56
6
5
11
22 3
7 4, 8
12

GENERAL INFORMATION
FOUR-WHEEL ANTI-LOCK BRAKE SYSTEM (4ABS)35B-3
MAIN COMPONENTS AND FUNCTIONS
.
Parts nameNo.Functional description
SensorWheel speed sensor1Outputs the frequency signal in proportion to the
rotation speed of each wheel to ABS-ECU.
Magnetic encoder for
wheel speed detection2The wheel speed sensor is a pulse generator. When
the magnetic encoder for wheel speed detection (a
plate on which north and south pole sides of the
magnets are arranged alternately) rotates, it outputs
frequency pulse signal in proportion to each wheel
speed.
Stop light switch3Outputs the signal indicating whether the brake pedal
is depressed or not through ETACS-ECU to ABS-ECU
via the CAN line.
ActuatorHydraulic unit4Drives the solenoid valve using the signal from
ABS-ECU, and controls the brake fluid pressure for
each wheel.
ABS warning light5Informs the driver of the system status by illuminating,
flashing, or turning off the warning light according to
the signal from ABS-ECU.
Brake warning light6Used as the warning light for the parking brake, brake
fluid level, and EBD control. Informs the driver of the
system status by illuminating or turning off the warning
light according to the signal from ABS-ECU, ETACS or
combination meter.
Data link connector7Establishes the communication with scan tool.
ABS control unit (ABS-ECU)8Controls the actuators (described above) based on the
signals coming from each sensors.
Controls the self-diagnostic functions and fail-safe
functions.
Controls diagnostic function (Compatible with scan
tool).

GENERAL INFORMATION
FOUR-WHEEL ANTI-LOCK BRAKE SYSTEM (4ABS)35B-4
SYSTEM CONFIGURATION
NOTE: Dashed lines indicate the CAN bus communi-
cation lines.
.
AC608528AB
Wheel speed sensor (FL)
ECU power supplyABS-ECU
Combination meter
(Brake warning lamp,
ABS warning lamp)
Data link connector Wheel speed sensor (RL)
Wheel speed sensor (RR)
Wheel speed sensor (FR)
Stop light switch Front-right wheel (FR)
Hydraulic unit Stop light switch
ETACS-ECU
Wheel
speed
sensor
(FL) Wheel
speed
sensor
(FR)Wheel
speed
sensor
(RR)
Wheel
speed
sensor
(RL) Control solenoid valve (RL) OUT Control solenoid valve (RR) OUT Control solenoid valve (FL) OUT Control solenoid valve (FR) OUT Control solenoid valve (FR) IN
Control solenoid valve (FL) IN
Control solenoid valve (RR) IN
Control solenoid valve (RL) IN
Rear right wheel (RR)
Rear left wheel (RL) Front left wheel (FL)

GENERAL INFORMATION
FOUR-WHEEL ANTI-LOCK BRAKE SYSTEM (4ABS)35B-5
ABS ELECTRICAL DIAGRAM
AC609237
Ignition
switch (IG1) Fusible
link No.34Fusible
link No.36 Fusible
link No.27Fusible
link No.26
Analog
interface
circuitAnalog
interface
circuit CAN drive circuit
Interface circuit
Solenoid valve Stoplight
switch
Motor Hydraulic unitStoplightEngine
control
module Data link
connector
Solenoid valve
power supplySolenoid valve
power supply
Motor power supplyMotor power supplyPower supplyCAN drive
circuit
Interface
circuit
CAN transceiver
circuit
CPU
LED drive
circuitInterface
circuit
Interface circuit
Wheel speed sensor (FL) (FR) (RL) (RR)Relay box
(Engine
compartment)
Combination
meter
AB
ABS-ECUCAN drive
circuit
Interface
circuit ETACS-ECU

CONSTRUCTION DESCRIPTION
FOUR-WHEEL ANTI-LOCK BRAKE SYSTEM (4ABS)35B-6
CONSTRUCTION DESCRIPTION
SENSORM2351001000494
Wheel speed sensor
The wheel speed sensor is a kind of a pulse genera-
tor. It consists of the magnetic encoder for wheel
speed detection (a plate on which north and south
pole sides of the magnets are arranged alternately)
which rotates at the same speed of the wheel and
the wheel speed sensor (semiconductor sensor).
This sensor outputs frequency pulse signals in pro
-
portion to the wheel speed.
The front wheel speed sensor consists of the front
wheel speed sensor mounted on the knuckle and the
magnetic encoder for wheel speed detection which is
press-fitted together with the oil seal to the front
wheel bearing. The rear wheel speed sensor con
-
sists of the rear wheel speed sensor mounted on the
trailing arm assembly and the magnetic encoder for
wheel speed detection which is press-fitted together
with the oil seal to the rear wheel bearing.
ACTUATORSM2351002000356
ABS warning light, Brake warning light
The ABS system informs the driver of the ABS sys-
tem status by illuminating, extinguishing, or flashing
the ABS warning light and brake warning light as fol
-
lows.
ABS warning light
•Turns ON when a system malfunction occurs.
Brake warning light
•Turns ON when an EBD system malfunction
occurs.
NOTE: .
•Turns ON when the brake fluid level in the
reservoir tank becomes the specified value or
lower.
•Turns ON when the parking brake lever is
pulled and the brake is activated.
ABS warning light and brake warning light illumination or flashing pattern
NOTE: *:ABS and brake warning lights remain illumi-
nated until the ignition is switched off.
AC608548
AB
FRONT REAR

Front wheel speed sensor
Rear wheel speed sensor
Encoder for wheel speed detection
Encoder for wheel speed detection
StateABS warning lightBrake warning light
NormalCorrect−−
FaultyABS failureIlluminates−
EBD failureIlluminatesIlluminates
When scan tool is
connectedActuator not operated−−
Actuator operatedFlash (2Hz)−
After actuator operated*Illuminates*Illuminates*

CONSTRUCTION DESCRIPTION
FOUR-WHEEL ANTI-LOCK BRAKE SYSTEM (4ABS)35B-7
ABS-ECUM2351003000520
•By integrating ABS-ECU into the hydraulic unit,
no wiring harness for sending drive signal of the
solenoid valve and pump motor is required,
assuring higher reliability.
•Self-diagnostic and memory functions are inte-
grated into ABS-ECU. If any malfunction is
detected by the self-diagnostic function,
ABS-ECU activates a fail-safe function and illumi
-
nates the ABS warning light and brake warning
light
*.
NOTE: *: The brake warning light is used as the
EBD control warning light.
•ABS-ECU detects vehicle speed from the signals
of the wheel speed sensor and its recognizes the
wheel rotation status, estimates the wheel slip
condition based on the preprogrammed algo
-
rithm, and then controls the solenoid valve in the
hydraulic unit so that the wheels do not lock.
ABS hydraulic pressure control
ABS control cycle
1. The ABS-ECU calculates the speed and deceler-
ation of each wheel based on the signals from the
four wheel speed sensors, and estimates the
vehicle speed at that time.
2. When the brake pedal is depressed, the brake
fluid pressure applied to the wheel cylinder
increases, and the wheel speed decreases.
When the difference between the wheel speed
and vehicle speed increases, and the vehicle
deceleration goes below the specified value (Point A), ECU determines that the wheels are
about to be locked. At this time, ECU reduces the
brake fluid pressure by outputting the pressure
decrease signal to the solenoid valves (IN, OUT).
(between a and b)
3. When the vehicle deceleration and wheel speed
begin recovery, and the vehicle speed reaches
the point B, ECU outputs the pressure hold signal
to maintain the wheel cylinder fluid pressure.
(between b and c)
AC506830AB
a
b
cd A
BC
D
e Increase
Hold
Decrease
Wheel speed
Brake pressureActual vehicle speedEstimated vehicle speed