Anti-Lock Brake System (For Sedan) System Description

Brake. Yaris. Ncp93, 131
Brake Control Dynamic Control Systems. Yaris. Ncp93, 131

  1. FUNCTION DESCRIPTION

  1. ABS with EBD OPERATION

  1. INITIAL CHECK

  1. FUNCTION OF COMPONENTS

Anti-Lock Brake System (For Sedan) -- System Description



FUNCTION DESCRIPTION
HINT:
The skid control ECU is located within the brake actuator assembly.

  1. ABS (Anti-lock Brake System)
    The ABS helps prevent the wheels from locking when the brakes are applied firmly or when braking on a slippery surface.

  2. EBD (Electronic Brake force Distribution)
    The EBD control utilizes ABS and performs proper brake force distribution between the front and rear wheels in accordance with driving conditions.
    When braking while cornering, it also controls the brake forces of the right and left wheels, helping to maintain vehicle stability.


ABS with EBD OPERATION

  1. Based on the signals received from each of the 4 wheel speed sensors, the skid control ECU calculates the speed of each wheel and checks the wheel slippage conditions. The ECU controls the pressure holding valve and pressure reduction valve in order to adjust the brake fluid pressure of each wheel cylinder in accordance with the slippage conditions.


INITIAL CHECK

  1. When the vehicle speed first reaches approximately 6 km/h (4 mph) or more after the ignition switch is turned to ON, each solenoid valve and motor in the brake actuator is sequentially activated to perform an electrical check. During the initial check, the operating sound of the solenoid valves and motors can be heard from the engine compartment, but this is not a malfunction.


FUNCTION OF COMPONENTS

Component
Function
Speed sensor
Detects the wheel speed and sends the signal to the skid control ECU.
Stop light switch assembly
Detects the brake operating conditions and inputs the results to the skid control ECU.
Main body ECU
Detects the parking brake operating conditions and inputs the results to the skid control ECU via CAN communication.
Skid control ECU
  1. Housed in the brake actuator assembly.
  2. Processes the signals sent from each sensor to control the ABS and EBD.
Brake actuator assembly
  1. Consists of the holding solenoid valve, pressure reduction solenoid valve, pump motor, and reservoir, and adjusts the brake fluid pressure applied to each wheel cylinder.
  2. Houses the skid control ECU.
Motor relay
  1. Supplies power to the pump motor.
  2. Housed in the skid control ECU.
Solenoid relay
  1. Supplies power to each solenoid.
  2. Housed in the skid control ECU.
ABS warning light
  1. Comes on to inform the driver that a malfunction in the ABS has occurred.
  2. Blinks to output DTC.
Brake warning light
  1. Comes on to inform the driver that the parking brake is ON when the system is normal, or that the brake fluid has decreased.
  2. Comes on to inform the driver that a malfunction in the EBD has occurred.
ECM
Controls the engine information and inputs the results to the skid control ECU via CAN communication.