Mazda X-5. Manual — part 61

ANTILOCK BRAKE SYSTEM

04–13–7

04–13

ABS CONTROL OUTLINE

E5U041343750N05

• ABS control occurs when wheel slip is determined by the ABS CM (based on the four ABS wheel-speed

sensors). Then, the ABS HU inlet and outlet solenoid valves are operated and brake fluid pressure is controlled
accordingly to prevent wheel lock-up.

• Use of ABS control during emergency braking or on slippery road surfaces allows directional stability to be

maintained, steerability ensured and stopping distance to be reduced.

• The ABS control system has independent front wheel control and unified control (select low) for the rear

wheels.

Note

• Select low control: A control system in which the left and right vehicle wheel speeds are compared and

brake fluid pressure is controlled according to the wheel most likely to lock-up.

Block Diagram

End Of Sie

CPU

HU

ABS WHEEL-SPEED
SENSOR (LF)

CALIPER PISTON (LF)

CALIPER PISTON (LR)

CALIPER PISTON (RF)

CALIPER PISTON (RR)

CM

SOLENOID
VALVE

PUMP
MOTOR

ABS HU/CM

ABS WHEEL-SPEED
SENSOR (RF)

ABS WHEEL-SPEED
SENSOR (LR)

ABS WHEEL-SPEED
SENSOR (RR)

C3U0413S009

ANTILOCK BRAKE SYSTEM

04–13–8

ABS CONTROL OPERATION

E5U041343750N06

• When the ABS CM determines wheel slip conditions based on the signals from the ABS wheel-speed sensors

during braking, the ABS CM operates the ABS HU inlet and outlet solenoid valves, reducing and maintaining
brake fluid pressure in accordance with the wheel slip factors. Then, when the wheel slip condition has passed,
brake fluid pressure is increased and maintained, ensuring braking with a constantly stable brake force.

Operating Condition Transition Diagram

End Of Sie

EBD CONTROL OUTLINE

E5U041343750N07

• EBD control uses the ABS system to control brake fluid pressure distribution to the rear wheels so that they do

not lock-up prior to the front wheels during braking, thereby preventing the loss of handling stability.

Features

• EBD control has independent control systems for both the front and rear wheels.

• EBD control constantly and properly distributes brake fluid pressure regardless of vehicle weight.

0

0

ESTIMATED VEHICLE SPEED

WHEEL SPEED

SPEED

SOLENOID VALVE CONTROL

BRAKE FLUID
PRESSURE

PRESSURE REDUCTION

TIME

PRESSURE MAINTAINED

PRESSURE INCREASE

HIGH

HIGH

TIME

C3U0413S010

ANTILOCK BRAKE SYSTEM

04–13–9

04–13

Block Diagram

End Of Sie

EBD CONTROL OPERATION

E5U041343750N08

• EBD control detects the slip ratio between the front and rear wheels from the ABS wheel-speed sensor signals.

If the slip ratio of the rear wheels as compared to the front wheels is larger than the fixed limit, the ABS HU/CM
reduces brake pressure being distributed to the rear wheels. Due to this, brake pressure distribution is
constantly controlled in the proper proportion and in relation to vehicle load, road surface conditions and
vehicle speed.

• Determination of the rear wheel slip ratio, based on a comparison of the lowest front wheel speed and the

estimated vehicle speed with the rear wheel speeds, is divided into conditions 0-4 shown in the table below.

• The ABS HU outlet and inlet solenoid valves are operated and the brake fluid pressure controlled according to

these conditions.

• If ABS control conditions are met during EBD control, EBD control is stopped and ABS control is given priority.

α

—

δ: Specified value

CPU

HU

ABS WHEEL-SPEED
SENSOR (LF)

CALIPER PISTON (LF)

CALIPER PISTON (LR)

CALIPER PISTON (RF)

CALIPER PISTON (RR)

CM

SOLENOID
VALVE

PUMP
MOTOR

ABS HU/CM

ABS WHEEL-SPEED
SENSOR (RF)

ABS WHEEL-SPEED
SENSOR (LR)

ABS WHEEL-SPEED
SENSOR (RR)

C3U0413S011

Conditi

on

Rear wheel slip ratio

determination

EBD control

Solenoid valve

Comment

0

No slip

No control

Pressure increase

—

1

α%—β%

Control

Pressure maintained

—

2

β% or more

Control

Pressure reduction/

maintained

—

3

After EBD control, slip ratio is

γ%

Control

Pressure increase/

maintained

—

4

Front wheel slip ratio is

δ% or more

Control

Pressure reduction/

maintained/ increase

ABS control operates

ANTILOCK BRAKE SYSTEM

04–13–10

Operating Condition Transition Diagram

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CONTROLLER AREA NETWORK (CAN) OUTLINE

E5U041343750N09

• The ABS HU/CM sends and receives data to and from other modules via the CAN system. Refer to Section 09

for a detailed explanation of the CAN. (See 09–40–1 CONTROLLER AREA NETWORK (CAN) SYSTEM
OUTLINE.)

Data sent

• Brake system condition

• Wheel speeds of all four wheels

• Brake system warning light illumination request

• ABS warning light illumination request

Data received

• Brake pedal position

• Tire size

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ABS WHEEL-SPEED SENSOR AND ABS SENSOR ROTOR FUNCTION

E5U041343720N01

• The ABS wheel-speed sensor and ABS sensor rotor detect the rotation condition of each wheel and transmit

this information to the ABS HU/CM.

• The signal from the ABS wheel-speed sensor is the primary signal that the ABS HU/CM uses when carrying

out control.

End Of Sie

4

3

2

1

0

0

0

VEHICLE SPEED

REAR
WHEEL SPEED

FRONT
WHEEL SPEED

FRONT BRAKE
FLUID PRESSURE

REAR BRAKE
FLUID PRESSURE

EBD INITIAL CONTROL VALUE

EBD CONTROL AREA

ABS INITIAL CONTROL VALUE

ABS CONTROL AREA

SPEED

REAR SOLENOID
VALVE CONTROL

BRAKE FLUID
PRESSURE

PRESSURE REDUCTION

TIME

PRESSURE MAINTAINED

PRESSURE INCREASE

HIGH

TIME

HIGH

C3U0413S012