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35B-1

GROUP 35B

FOUR-WHEEL

ANTI-LOCK BRAKE

SYSTEM (4ABS)

CONTENTS

GENERAL INFORMATION . . . . . . . .

CONSTRUCTION DESCRIPTION . . .

35B-2

35B-6

SENSOR . . . . . . . . . . . . . . . . . . . . . . . . . . .

ACTUATORS . . . . . . . . . . . . . . . . . . . . . . .

ABS-ECU. . . . . . . . . . . . . . . . . . . . . . . . . . .

35B-6

35B-6

35B-7

.

35B-2 FOUR-WHEEL ANTI-LOCK BRAKE SYSTEM (4ABS)

GENERAL INFORMATION

GENERAL INFORMATION

The ABS that ensures directional stability and con-

M2351000100830

The magnetic encoder for detecting the wheel trollability during hard braking. ABS is standard speed has been installed instead of the rotor as 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 system) control that can obtain ideal rear wheel brake force has been employed.

• the wheel speed sensor.

For wiring harness saving and secure data communication, 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

Item

ABS control type

Wheel speed sensor Magnetic encoder

Type

Front

Rear

Specifications

4 sensors

86 (N pole: 43, S pole: 43)

86 (N pole: 43, S pole: 43)

Semiconductor

.

CONSTRUCTION DIAGRAM

5 6

5

<Vehicles with rear drum brake>

SERVICE

REQUIRED

6

1 2

CHECK

4, 8

3

7

2

1

1

2

<Vehicles with rear disc brake>

AC608518 AB

.

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

GENERAL INFORMATION

MAIN COMPONENTS AND FUNCTIONS

Parts name

Sensor Wheel speed sensor

Actuator

Data link connector

Magnetic encoder for wheel speed detection

Stop light switch

Hydraulic unit

ABS warning light

Brake warning light

ABS control unit (ABS-ECU)

7

8

35B-3

No. Functional description

1 Outputs the frequency signal in proportion to the rotation speed of each wheel to ABS-ECU.

2

3

4

The 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.

Outputs the signal indicating whether the brake pedal is depressed or not through ETACS-ECU to ABS-ECU via the CAN line.

Drives the solenoid valve using the signal from

ABS-ECU, and controls the brake fluid pressure for each wheel.

5

6

Informs the driver of the system status by illuminating, flashing, or turning off the warning light according to the signal from ABS-ECU.

Used 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.

Establishes the communication with scan tool.

Controls 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).

35B-4 FOUR-WHEEL ANTI-LOCK BRAKE SYSTEM (4ABS)

GENERAL INFORMATION

SYSTEM CONFIGURATION

Wheel speed sensor (FL)

Wheel speed sensor (RL)

Wheel speed sensor (RR)

Wheel speed sensor (FR)

Stop light switch

ECU power supply

ABS-ECU

Control solenoid valve (FR) IN

Control solenoid valve (FR) OUT

Control solenoid valve (FL) IN

Control solenoid valve (FL) OUT

Control solenoid valve (RR) IN

Control solenoid valve (RR) OUT

Control solenoid valve (RL) IN

Control solenoid valve (RL) OUT

Combination meter

(Brake warning lamp,

ABS warning lamp)

Data link connector

Front-right wheel (FR)

Wheel speed sensor

(FR)

Rear right wheel (RR)

ETACS-ECU

Stop light switch

Wheel speed sensor

(RR)

Wheel speed sensor

(FL)

Front left wheel (FL)

.

NOTE: Dashed lines indicate the CAN bus communication lines.

Hydraulic unit

Wheel speed sensor

(RL)

Rear left wheel (RL)

AC608528AB

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

GENERAL INFORMATION

ABS ELECTRICAL DIAGRAM

Fusible link No.27

Fusible link No.26

Fusible link No.34

Ignition switch (IG1)

35B-5

Fusible link No.36

Relay box

(Engine compartment)

ETACS-ECU

CAN drive circuit

Interface circuit

CAN drive circuit

Analog interface circuit

Analog interface circuit

Interface circuit

CAN drive circuit

Interface circuit

Stoplight switch

Data link connector

Engine control module

Stoplight

Hydraulic unit

Solenoid valve

Motor

Solenoid valve power supply

Motor power supply

Solenoid valve power supply

ABS-ECU

(FL)

Motor power supply Power supply

CAN transceiver circuit

CPU

LED drive circuit

Interface circuit

Interface circuit

Combination meter

(FR) (RL)

Wheel speed sensor

(RR)

AC609237 AB

35B-6 FOUR-WHEEL ANTI-LOCK BRAKE SYSTEM (4ABS)

CONSTRUCTION DESCRIPTION

SENSOR

Wheel speed sensor

CONSTRUCTION DESCRIPTION

FRONT REAR

<Vehicles with rear drum brake>

M2351001000494

<Vehicles with rear disc brake>

Front wheel speed sensor

Rear wheel speed sensor

Encoder for wheel speed detection

The wheel speed sensor is a kind of a pulse generator. 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 proportion to the wheel speed.

Encoder for wheel speed detection

AC608548AB

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 consists 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.

ACTUATORS

ABS warning light, Brake warning light

The ABS system informs the driver of the ABS system status by illuminating, extinguishing, or flashing the ABS warning light and brake warning light as follows.

ABS warning light

• Turns ON when a system malfunction occurs.

M2351002000356

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

State ABS warning light

Normal

Faulty

Correct

ABS failure

Illuminates

When scan tool is connected

EBD failure

Actuator not operated

Actuator operated

After actuator operated

*

NOTE:

*

:ABS and brake warning lights remain illuminated until the ignition is switched off.

Illuminates

Flash (2Hz)

Illuminates

*

Brake warning light

Illuminates

Illuminates

*

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

CONSTRUCTION DESCRIPTION

ABS-ECU

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 integrated into ABS-ECU. If any malfunction is detected by the self-diagnostic function,

ABS-ECU activates a fail-safe function and illuminates the ABS warning light and brake warning light

*

.

35B-7

M2351003000520

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 algorithm, and then controls the solenoid valve in the hydraulic unit so that the wheels do not lock.

ABS hydraulic pressure control

ABS control cycle

Increase

Hold

Decrease

Wheel speed

Estimated vehicle speed

A

C

D

B

Actual vehicle speed

a

Brake pressure

e d b c

1. The ABS-ECU calculates the speed and deceleration 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

AC506830AB

(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)

35B-8 FOUR-WHEEL ANTI-LOCK BRAKE SYSTEM (4ABS)

CONSTRUCTION DESCRIPTION

4. When the wheel speed deceleration is further recovered and overpasses the point C, ECU determines that the wheel lock possibility has been eliminated and increases the brake fluid pressure by outputting the pressure increase signal again. (between c and d)

5. Brake fluid pressure is controlled by repeating the increase and hold of the pressure. (between d and e)

6. When the wheel deceleration goes below the threshold again, ABS-ECU controls the brake fluid pressure by repeating the cycle (Step 2 to 5).

Four-wheel control

ABS fluid pressure is controlled independently for four wheels.

EBD fluid pressure control

EBD operating conceptual design

Braking force distribution by EBD control

Ideal distribution curve when seated by fixed persons

Rear braking force

Braking force distribution curve by the existing proportioning valve

Ideal distribution curve when seated by one persons

Front braking force

Braking Force

Improved

EBD control is activated in a range with lower slip ratio where ABS is disabled. EBD calculates vehicle deceleration and slip amount of the four wheels based on the wheel speed sensor signal. If the rear wheel speed differs from the vehicle speed by a certain level or more, EBD increases, holds, and decreases the pressure at the rear wheel control solenoid valve in the hydraulic unit, and then adjusts rear wheel brake fluid pressure fairly close to an ideal distribution curve.

INITIAL CHECK

ABS-ECU performs the following initial checks using the diagnostic functions. ABS-ECU illuminates the

ABS warning light for 3 seconds (including the initial check)

*

after the ignition switch is turned ON. If any malfunction is detected, ABS-ECU continues illuminating the ABS warning light and disables ABS control.

AC208548AB

NOTE:

*

: The ABS warning light may stay on after the ignition switch is turned ON until the startup vehicle speed reaches approximately 10 km/h (6 mph).

As the ABS-ECU memorizes any diagnostic trouble code related to the wheel speed sensor malfunction recorded during the previous ignition ON status,

ABS-ECU continues illuminating the ABS warning light until it verifies that the malfunction for that code is resolved (startup check).

.

INITIAL CHECK

Performs self-diagnosis in ABS-ECU.

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

CONSTRUCTION DESCRIPTION

STARTUP CHECK

.

When the startup vehicle speed reaches approximately 10 km/h (6 mph), ABS-ECU performs the following checks.

1. Motor, solenoid valve check (Initial startup

*

only)

Turns ON the motor relay in ECU, and checks the pump motor operation. At the same time,

ABS-ECU sequentially energizes each solenoid valve in a very short period and checks the valve operation.

NOTE:

*

: Initial startup indicates a first startup after the system has started.

2. Wheel speed sensor check

ABS-ECU checks for any wheels that have not received wheel speed sensor signal from the startup.

CONSTANT CHECK

.

ABS-ECU constantly checks the following items.

1. ABS-ECU

Performs self-diagnosis in ECU.

35B-9

2. ECU power supply

Checks if ECU power supply voltage stays within the operational range.

3. Wheel speed sensor

(1) Monitors the output voltage of the sensor signal wiring harness and checks for abnormal output voltage (open/short circuit).

(2) Checks for any wheels that do not send pulse signal while the vehicle is in motion.

(3) Checks if wheel speed which is abnormally higher or lower than the vehicle speed is input.

4. Pump motor, solenoid valve

Checks that the ABS-ECU output signal and the operating conditions of the pump motor and solenoid valve agree with each other.

CAN COMMUNICATION

ABS-ECU outputs the ABS warning light and the

EBD warning light

*

illumination request signals to the combination meter through CAN communication.

NOTE: *: The brake warning light is used as EBD control warning light.

FAIL-SAFE FUNCTION

If any malfunction is detected by the self-diagnostic function, ABS-ECU illuminates the ABS warning light and brake warning light

*

, and it disables ABS and

EBD control.

DTC

No.

Item Countermeasures for failure

EBD control

NOTE: *: The brake warning light is used as EBD control warning light.

ABS control Brake warning light

ABS warning light

C100A Abnormality in FL wheel speed sensor circuit

C1015 Abnormality in FR wheel speed sensor circuit

C1020 Abnormality in RL wheel speed sensor circuit

C102B Abnormality in RR wheel speed sensor circuit

C1011 Abnormality in FL wheel speed sensor signal

C101C Abnormality in FR wheel speed sensor signal

C1027 Abnormality in RL wheel speed sensor signal

C1032 Abnormality in RR wheel speed sensor signal

Executed

(Prohibited when two or more wheels are faulty.)

Executed

(Prohibited when two or more wheels are faulty.)

Prohibited

Prohibited

Extinguished

*2

Extinguished

*2

Illuminated

*3

Illuminated

*3

35B-10

DTC

No.

Item

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

CONSTRUCTION DESCRIPTION

Countermeasures for failure

EBD control ABS control

Prohibited

Brake warning light

Extinguished

*2

ABS warning light

Illuminated

*3

C1014 Mutual monitoring of FL wheel speed sensor

C101F Mutual monitoring of FR wheel speed sensor

C102A Mutual monitoring of RL wheel speed sensor

C1035 Mutual monitoring of RR wheel speed sensor

C1041 Abnormality in periodical signal for FL wheel speed sensor

C1042 Abnormality in periodical signal for FR wheel speed sensor

C1043 Abnormality in periodical signal for RL wheel speed sensor

C1044 Abnormality in periodical signal for RR wheel speed sensor

C1046 FL wheel speed sensor control phase time exceeded

C1047 FR wheel speed sensor control phase time exceeded

C1048 RL wheel speed sensor control phase time exceeded

C1049 RR wheel speed sensor control phase time exceeded

C104B Abnormality in FL wheel inlet valve system

C104F Abnormality in FR wheel inlet valve system

C1053 Abnormality in RL wheel inlet valve system

C1057 Abnormality in RR wheel inlet valve system

C105F Abnormality in FL wheel outlet valve system

C1063 Abnormality in FR wheel outlet valve system

C1067 Abnormality in RL wheel outlet valve system

C105B Abnormality in RR wheel outlet valve system

C2104 Malfunction of valve power supply circuit

C1073 Malfunction of motor drive circuit

Executed

(Prohibited when two or more wheels are faulty.)

Executed

(Prohibited when two or more wheels are faulty.)

Executed

(Prohibited when two or more wheels are faulty.)

Prohibited

Prohibited

Prohibited

Executed

Prohibited

Prohibited

Prohibited

Prohibited

Prohibited

Prohibited

Extinguished

Extinguished

Illuminates

Illuminates

Illuminates

Extinguished

*2

*2

Illuminated

Illuminated

Illuminates

Illuminates

Illuminates

Illuminated

*3

*3

*3

.

DTC

No.

Item

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

CONSTRUCTION DESCRIPTION

Countermeasures for failure

EBD control ABS control

C2116 Abnormality in pump motor power supply voltage

C1000 Abnormality in stop light switch circuit

C2200 Abnormality in ABS-ECU

C2100 Battery voltage problem (low voltage)

9.7

±

0.3 V or less

*1

8.0

±

0.5 V or less

*1

Executed

Executed

Prohibited

Executed

Prohibited

C2101 Battery voltage problem (high voltage)

18.0 more

± 1.0 V or Prohibited

C1395 Brake fluid filling not completed Executed

C2203 VIN not written

C1608 Implausible diagnosis data

U0001 Bus off

U0100 Engine time-out error

Executed

Executed

Executed

Executed

U0141 ETACS time-out error Executed

U1415 Variant coding not implemented Executed

U1417 Invalid variant coding value

(including wrong assembly)

Executed

NOTE: .

*1

This diagnostic trouble code is not set within the vehicle speed of 20 km/h (12 mph) or less.

*2

Turns ON when two or more wheels are faulty.

*3

Stays ON until the vehicle speed reaches 10 km/h (6 mph) when the ignition switch is turned to

ON next time.

DIAGNOSTIC FUNCTION

ABS-ECU has the following functions for easier system checks. The following items can be diagnosed using scan tool.

Diagnostic trouble code set

Service data output

Actuator test

Prohibited

Executed

Prohibited

Prohibited

Prohibited

Prohibited

Executed

Executed

Executed

Executed

Executed

Executed

Prohibited

Prohibited

Brake warning light

Extinguished

ABS warning light

Illuminated

*3

Extinguished

Illuminates

Extinguished

Illuminates

Illuminates

Extinguished

Extinguished

Extinguished

Extinguished

Extinguished

Extinguished

Extinguished

Extinguished

35B-11

Extinguished

Illuminates

Illuminates

Illuminates

Illuminates

Flashes (1 Hz)

Illuminates

Extinguished

Extinguished

Extinguished

Extinguished

Illuminates

Illuminates

DIAGNOSTIC TROUBLE CODE SET

There are 43 diagnosis items. Since all the diagnostic results are recorded in volatile memory

(EEPROM*), they are stored in the memory even though the battery terminals are disconnected.

NOTE: .

*EEPROM (Electrical Erasable & Programmable

ROM): Special type of memory that can be pro-

grammed or erased electrically

For each diagnosis item, refer to Service Manual.

.

SERVICE DATA OUTPUT

Using scan tool, the input data sent from the sensors and switches can be read.

NOTE: For service data items, refer to Service Manual.

.

35B-12

ACTUATOR TEST

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

CONSTRUCTION DESCRIPTION

Using scan tool, the actuators can be forcibly operated.

NOTE: .

When ABS-ECU is disabled, the actuator test cannot be performed.

The actuator test can be performed only when the vehicle is stationary. When the vehicle speed reaches 10 km/h (6 mph), the forcible actuator operation is disabled.

During actuator test, the ABS warning light flashes in 2Hz, and ABS control is prohibited.

For the actuator test specification, refer to Service Manual.

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