Abs Cm Part Function; Function Table; Abs Control Outline; Block Diagram - Mazda RX-8 2004 Service Highlights

ABS CM PART FUNCTION

• The ABS CM detects the vehicle wheel speeds based on the signals from the four ABS wheel- speed sensors.
The CM calculates the rotation condition of each wheel from the relation between the detected vehicle wheel
speed and the estimated (based on the detected speed) vehicle speed from there on. It then accordingly
controls brake fluid pressure to each wheel to prevent lock-up.

Function Table

Function name
ABS control function
Electronic brakeforce distribution (EBD) control
function
Vehicle speed output function
On-board diagnostic system
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ABS CONTROL OUTLINE

• 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

ABS WHEEL-SPEED
SENSOR (LF)
ABS WHEEL-SPEED
SENSOR (RF)
ABS WHEEL-SPEED
SENSOR (LR)
ABS WHEEL-SPEED
SENSOR (RR)
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04–13–6
ANTILOCK BRAKE SYSTEM
• Controls brake fluid pressure when braking to maintain directional
stability, ensure steerability and reduce stopping distance.
• Constantly controls proper distribution of brake fluid pressure to the front
and rear wheels according to vehicle load, road surface and vehicle
speed conditions to prevent early lock-up of the rear wheels.
• Outputs the vehicle speed signal to the audio unit, car-navigation unit
and the auto leveling control module.
• Outputs the wheel speed signal and ABS system warning control data
via CAN lines.
• Main components of the ABS control system have a self-diagnosis
function. In case a malfunction occurs, warning lights illuminate to alert
the driver, and at the same time a DTC is stored in the ABS HU/CM.
• When a malfunction is determined as a result of on-board diagnosis,
system control is suspended or limited to prevent any dangerous
situation while driving.
ABS HU/CM
CM
SOLENOID
VALVE
CPU
Contents
HU
CALIPER PISTON (LF)
CALIPER PISTON (RF)
PUMP
MOTOR
CALIPER PISTON (LR)
CALIPER PISTON (RR)
CHU041343750S04
CHU041343750S05
CHU0413S009