Nissan Quest E52. Instruction — part 230
SYSTEM
BRC-13
< SYSTEM DESCRIPTION >
[WITH VDC]
C
D
E
G
H
I
J
K
L
M
A
B
BRC
N
O
P
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
*
.
• 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]
C
D
E
G
H
I
J
K
L
M
A
B
BRC
N
O
P
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.
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