System Description
- By preventing wheel lock through brake force (brake fluid pressure) control that is electronically controlled by detecting wheel speed during braking, stability during emergency braking is improved so that obstacles can be easily bypassed by steering operation.
- During braking, control units calculate wheel speed and pseudo-vehicle speed, and transmits pressure increase, hold or decrease signals to actuator portion according to wheel slip status.
- The following effects are obtained by preventing wheel lock during braking:
- Vehicle tail slip is prevented during braking when driving straight.
- Understeer and oversteer tendencies are moderated during braking driving on a corner.
- Obstacles may be easily bypassed by steering operation during braking.
- Slight vibrations are felt on the brake pedal and the operation noises occur, when ABS function operates. This is not a malfunction because it is caused by ABS function that is normally operated.
- CONSULT can be used to diagnose the system diagnosis.
- Fail-safe function is adopted. When a malfunction occurs in ABS function, the control is suspended for VDC function and TCS function. The vehicle status becomes the same as models without VDC function, TCS function and ABS function. However, EBD function is operated normally. Refer to Fail-safe .
NOTE:
- To stop vehicle efficiently, ABS does not operate and ordinary brake operates at low speed [approx. 3.1 to 6.2 MPH (5 to 10 km/h) or less, but differs subject to road conditions).
- Self-diagnosis is performed immediately after engine starts and when vehicle initially is driven [by vehicle speed approx. 9.3 MPH (15 km/h)]. Motor sounds are generated during self-diagnosis. In addition, brake pedal may feel heavy when depressing brake pedal lightly. These symptoms are not malfunctions.
SYSTEM DIAGRAM
INPUT AND OUTPUT SIGNALS
Major signal transmission between each unit via communication lines is shown in the following table:
| Component | Signal description |
|---|---|
| Yaw rate/side/decel G sensor | Mainly transmits the following signals to ABS actuator and electric unit (control unit) via communication line*1:
|
| Transfer control unit *2 | Mainly receives the ABS warning lamp signal from ABS actuator and electric unit (control unit) via CAN communication. |
| Combination meter | Mainly receives the ABS warning lamp signal from ABS actuator and electric unit (control unit) via CAN communication. |
*1: Communication line between yaw rate/side/decel G sensor and ABS actuator and electric unit (control unit)
*2: Models with 4WD system