Mazda X-5. Manual - part 61

 

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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

End Of Sie

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

End Of Sie

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

 

 

 

 

 

 

 

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