Nissan Quest E52. Manual - part 230

SYSTEM

BRC-13

< SYSTEM DESCRIPTION >

[WITH VDC]

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SYSTEM

System Description

INFOID:0000000009651357

• 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 and brake limited slip differential (BLSD) 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.

JSFIA0967GB

BRC-14

< SYSTEM DESCRIPTION >

[WITH VDC]

SYSTEM

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

VALVE OPERATION [VDC FUNCTION, TCS FUNCTION AND BRAKE LIMITED SLIP DIFFEREN-
TIAL (BLSD) FUNCTION

Component

Signal description

Yaw rate/side G sensor

Mainly transmits the following signals to ABS actuator and electric unit (control unit) via com-

munication line

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• Yaw rate signal
• Side G sensor signal

ECM

Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN 
communication.
• Accelerator pedal position signal
• Engine speed signal
Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN 
communication.
• Target throttle position signal

TCM

Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN 
communication.
• Shift position signal
• Current gear position signal
• P range signal
• N range signal
• R range signal

Steering angle sensor

Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN 
communication.
• Steering angle sensor signal

Combination meter

Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN 
communication.
• Brake fluid level switch signal
Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN 
communication.
• ABS warning lamp signal
• Brake warning lamp signal
• VDC warning lamp signal
• VDC OFF indicator lamp signal

SYSTEM

BRC-15

< SYSTEM DESCRIPTION >

[WITH VDC]

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The following descriptions explains the control of front brake right side, as an example.

When Pressure Increases

The control unit closes the cut valve 1 port and opens the suction valve 1 port by supplying current to the cut
valve 1 and the suction valve 1. Fluid pressure generated in the master cylinder passes through the suction
valve 1 and the fluid pressure is pressurized by the pump. Since power is not applied to the ABS IN valve and
the ABS OUT valve, the port of ABS IN valve is open and that of the ABS out valve is closed. This enables the
supply of intensified fluid pressure to the front RH caliper.

When Pressure Holds

The control unit closes the cut valve 1 port by supplying current to the cut valve 1. Since power is not applied
to the suction valve 1, the suction valve 1 port closes. The ABS IN valve port opens and the ABS OUT valve
port closes because power is not supplied to the ABS OUT valve. Since each port of the cut valve 1 and suc-

JSFIA0968GB

BRC-16

< SYSTEM DESCRIPTION >

[WITH VDC]

SYSTEM

tion valve 1 is closed, the paths to the master cylinder, front RH caliper, and pump and reservoir are cut to
maintain fluid pressure of the front RH caliper.

When Pressure Decreases

Since power is not supplied to the cut valve 1, suction valve 1, ABS IN valve, and ABS OUT valve, each port
of the suction valve 1 and the ABS OUT valve is closed and the ports of the cut valve 1 and the ABS IN valve
are open. This allows front RH caliper fluid pressure to flow into the cylinder side.

Component Parts and Function

VALVE OPERATION (ABS FUNCTION AND EBD FUNCTION)

Component

Function

Pump

Feeds brake fluid by the motor.

Motor

Activates the pump according to signals from ABS actuator and electric unit (control unit).

ABS IN valve

Switches the fluid pressure line to increase or hold according to signals from control unit.

ABS OUT valve

Switches the fluid pressure line to increase, hold or decrease according to signals from control unit.

Cut valve 1
Cut valve 2

Shuts off the ordinary brake line from master cylinder, when VDC function, TCS function and brake 
limited slip differential (BLSD) function are activated.

Suction valve 1
Suction valve 2

Supplies the brake fluid from master cylinder to the pump, when VDC function, TCS function and 
brake limited slip differential (BLSD) function are activated.

Inlet valve

Brake fluid sucked from the reservoir by the pump does not backflow.

Outlet valve

Brake fluid discharged from the pump does not backflow.

Return check valve

Returns the brake fluid from brake caliper and wheel cylinder to master cylinder by bypassing orifice 
of each valve when brake is released.

Pressure sensor

Detects the brake fluid pressure and transmits signal to control unit.

Reservoir

Temporarily reserves the brake fluid drained from brake caliper, so that pressure efficiently decreas-
es when decreasing pressure of brake caliper and wheel cylinder.

Damper

Reduces the vibrations travelling to the brake pedal during the operation of the VDC function, TCS 
function, ABS function, EBD function, or brake limited slip differential (BLSD) function.