System Description

SYSTEM

System Description

- The system switches fluid pressure of each brake caliper to increase, to hold or to decrease according to signals from control unit in ABS actuator and electric unit (control unit). This control system is applied to
VDC function, TCS function, ABS function, EBD function, hill start assist function, Rise-up & Build-up function, Brake force distribution function and Active trace control function.
- Fail-safe function is available for each function and is activated by each function when system malfunction occurs.

SYSTEM DIAGRAM







INPUT SIGNAL AND OUTPUT SIGNAL

Major signal transmission between each unit via communication lines is shown in the following table.
VDC function, TCS function, ABS function, EBD function, Rise-up & Build-up function and Brake force distribution function





*1: Communication line between yaw rate/side/decel G sensor and ABS actuator and electric unit (control unit)
*2: Models with 4WAS
Active trace control function





*: Communication line between yaw rate/side/decel G sensor and ABS actuator and electric unit (control unit)

VALVE OPERATION (ABS AND EBD)

Each valve is operated and fluid pressure of brake caliper is controlled.
When ordinary brake is applied and ABS is in operation (when pressure increases).










- Motor is activated. Brake fluid is pressurized by pump and is sent to secondary line through cut valve 2. At the same time, pressurized brake fluid is supplied to front RH caliper through ABS IN valve.
- Motor is activated. Brake fluid is pressurized by pump and is sent to primary line through cut valve 1. At the same time, pressurized brake fluid is supplied to front LH wheel caliper through ABS IN valve.
- Motor is activated. Brake fluid is pressurized by pump and is sent to primary line through cut valve 1. At the same time, pressurized brake fluid is supplied to rear RH wheel caliper through ABS IN valve.
- Motor is activated. Brake fluid is pressurized by pump and is sent to secondary line through cut valve 2. At the same time, pressurized brake fluid is supplied to rear LH wheel caliper through ABS IN valve.
When ABS operation starts (when pressure holds)










- Motor is activated. Brake fluid is pressurized by pump and is sent to secondary line through cut valve 2. At the same time, because ABS IN valve and ABS OUT vale are closed, fluid pressure holds.
- Motor is activated. Brake fluid is pressurized by pump and is sent to primary line through cut valve 1. At the same time, because ABS IN valve and ABS OUT vale are closed, fluid pressure holds.
- Motor is activated. Brake fluid is pressurized by pump and is sent to primary line through cut valve 1. At the same time, because ABS IN valve and ABS OUT vale are closed, fluid pressure holds.
- Motor is activated. Brake fluid is pressurized by pump and is sent to secondary line through cut valve 2. At the same time, because ABS IN valve and ABS OUT vale are closed, fluid pressure holds.
ABS is in operation (when pressure decreases)










- Being supplied to reservoir through ABS OUT valve, the fluid pressure of brake caliper is decreased.
- Being supplied to reservoir through ABS OUT valve, the fluid pressure of brake caliper is decreased.
- Being supplied to reservoir through ABS OUT valve, the fluid pressure of brake caliper is decreased.
- Being supplied to reservoir through ABS OUT valve, the fluid pressure of brake caliper is decreased.
Component Parts and Function





VALVE OPERATION (OTHER THAN ABS AND EBD)

Each valve is operated and fluid pressure of brake caliper is controlled.
NOTE:
There is no operation to hold and increase pressure for functions other than ABS and EBD.
When Pressure Increases











- Motor is activated. Brake fluid from pump is supplied to front RH wheel caliper through ABS IN valve. For other wheel, ABS IN valve is closed and brakes fluid is not supplied to caliper.
- Motor is activated. Brake fluid from pump is supplied to front LH wheel caliper through ABS IN valve. For other wheel, ABS IN valve is closed and brakes fluid is not supplied to caliper.
- Motor is activated. Brake fluid from pump is supplied to front RH wheel caliper through ABS IN valve. For other wheel, ABS IN valve is closed and brakes fluid is not supplied to caliper.
- Motor is activated. Brake fluid from pump is supplied to front LH wheel caliper through ABS IN valve. For other wheel, ABS IN valve is closed and brakes fluid is not supplied to caliper.
Released










- Being returned to master cylinder through ABS IN valve, fluid pressure of brake caliper is decreased.
- Being returned to master cylinder through ABS IN valve, fluid pressure of brake caliper is decreased.
- Being returned to master cylinder through ABS IN valve, fluid pressure of brake caliper is decreased.
- Being returned to master cylinder through ABS IN valve, fluid pressure of brake caliper is decreased.
Component Parts and Function






CONDITION FOR TURN ON THE WARNING LAMP

ABS Warning Lamp
- Turns ON at the same time as VDC warning lamp when either ABS function or EBD function is malfunctioning.
- Turns ON when ignition switch turns ON and turns OFF when the system is normal, for bulb check purposes.





Brake Warning Lamp
- Turns ON at the same time as ABS warning lamp and VDC warning lamp when EBD function is malfunctioning.
- Turns ON when ignition switch turns ON and turns OFF when the system is normal, for bulb check purposes.





VDC Warning Lamp
- Turns ON when either VDC function, TCS function, ABS function or EBD function is malfunctioning.
- Turns ON when ignition switch turns ON and turns OFF when the system is normal, for bulb check purposes.





IBA OFF indicator lamp
- Turns ON when Active trace control function is malfunctioning.
NOTE:
Lamp ON condition of intelligent brake assistance OFF indicator lamp is that intelligent brake assistance OFF
switch is in the pressed and not turned ON status.

CONDITION FOR TURN ON THE INDICATOR LAMP

VDC OFF indicator lamp
- Turns ON when VDC function and TCS function are switched to non-operational status (OFF) by VDC OFF
switch.
- Turns ON when ignition switch turns ON and turns OFF when the system is normal, for bulb check purposes.