INFINITI QX56 2011 Factory Service Manual

BRC-14
< SYSTEM DESCRIPTION >[WITH VDC]
COMPONENT PARTS
ABS Actuator and Electric Unit (Control Unit)
INFOID:0000000006222561
Electric unit (control unit) is in tegrated with actuator and motor/accumulator assembly and comprehensively
controls VDC function, TCS function, AB S function, EBD function, hill start assist function or brake limited slip
differential function.
ELECTRIC UNIT (CONTROL UNIT)
 Brake fluid pressure, engine and transmission are controlled according to signals from each sensor.
 If malfunction is detected, the system enters fail-safe mode.
ACTUATOR
The following components are integrated with ABS actuator.
Motor/accumulator Assembly
Pump Operates the pump drive according to signals from ABS actuator and electric unit (control unit) by the motor.
Motor Operates the motor drive according to signals fr om ABS actuator and electric unit (control unit).
Accumulator
 The accumulator accumulates brake fluid conveyed by the motor and pump.
Motor Relay
Operates the motor ON/OFF according to signals fr om ABS actuator and electric unit (control unit).
Actuator Relay (Main Relay)
Operates each valve ON/OFF according to signals fr om ABS actuator and electric unit (control unit).
ABS IN Valve and ABS OUT Valve
Increases, holds or decreases the fluid pressure of each caliper according to signals from ABS actuator and
electric unit (control unit).
Cut Valve 1, Cut Valve 2
Shuts off the ordinary brake line from master cylinder to signals from ABS actuator and electric unit (control
unit).
Suction Valve 1
Suction Valve 1 switches the brake path to convey accu mulator pressure to the front system, according to a
signal transmitted from the ABS actuat or and electric unit (control unit).
Suction Valve 2
Suction valve 2 releases accumulator pressure, accord ing to a signal transmitted from the ABS actuator and
electric unit (control unit).
Control Pressure Sensor (models with Advanced Driver Assistance System)
Detects the brake fluid pressure of brake caliper side and transmits a signal to ABS actuator and electric unit
(control unit).
Accumulator Pressure Sensor
The accumulator pressure sensor detects brake fluid pressure accumulated in the accumulator and conveys
the detected result to the ABS act uator and electric unit (control unit).
Master cylinder Pressure Sensor
Detects the brake fluid pressure of master cylinder part and transmits a signal to ABS actuator and electric unit
(control unit).
Wheel Sensor and Sensor RotorINFOID:0000000006222562
NOTE:
 Wheel sensor and sensor rotor is integrated in wheel hub assembly.
 Never measure resistance and voltage value using a tester because sensor is active sensor.
Revision: 2010 May2011 QX56

COMPONENT PARTSBRC-15
< SYSTEM DESCRIPTION > [WITH VDC]
C
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BRC
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 Downsize and weight reduction is aimed. IC for detection portion and magnet for sensor rotor are adopted.
 Power supply is supplied to detection portion so that magnetic field
line is read. Magnetic field that is detected is converted to current
signal.
 When sensor rotor rotates, magnetic field changes. Magnetic field
change is converted to current signals (rectangular wave) and is
transmitted to ABS actuator and electric unit (control unit). Change
of magnetic field is pr oportional to wheel speed.
Stop Lamp SwitchINFOID:0000000006222563
Detects the operation status of brake pedal and transmits converted electric signal to ABS actuator and elec-
tric unit (control unit).
Steering Angle SensorINFOID:0000000006222564
Detects the following information and transmits steering angle signal to ABS actuator and electric unit (control
unit) via CAN communication.
 Steering wheel rotation amount
 Steering wheel rotation angular velocity
 Steering wheel rotation direction
Yaw Rate/Side/Decel G sensorINFOID:0000000006222565
Calculates the following information that affects the v ehicle and transmits a signal to ABS actuator and electric
unit (control unit) via communication lines.
 Vehicle rotation angular velocity (yaw rate signal)
 Vehicle lateral acceleration (side G signal) / longitudinal acceleration (decel G signal)
Brake Fluid Level SwitchINFOID:0000000006222566
Detects the brake fluid level in reservoir tank and trans mits converted electric signal from ABS actuator and
electric unit (control unit), when brake fluid level is the specified level or less.
Parking Brake SwitchINFOID:0000000006222567
Detects the operation status of parking brake switch and transmits converted electric signal from combination
meter to ABS actuator and electric unit (control unit).
VDC OFF SwitchINFOID:0000000006222568
 VDC OFF switch is integrated in SNOW MODE / TOW MODE / VDC OFF switch assembly (2WD models) or
4WD switch assembly (4WD models).
 The operation of the VDC OFF switch enables the arbi trary switching of the VDC function between stop sta-
tus and standby status. The status of the function is indicated by the VDC OFF indicator lamp. (ON: Non-
operational status, OFF: Standby status)
- VDC function NOTE:
Brake limited slip differentia l (BLSD) control operates.
- TCS function
 VDC OFF indicator lamp turns OFF (standby status) when the engine is started again after it is stopped once while VDC OFF indicator lamp is ON (non-operational status).
JPFIC0131GB
Revision: 2010 May2011 QX56

BRC-16
< SYSTEM DESCRIPTION >[WITH VDC]
SYSTEM
SYSTEM
System DescriptionINFOID:0000000006222569
 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 func tion, EBD function, hill start assist function and brake limited slip dif-
ferential (BLSD) function
 Fail-safe function is available for each function and is activated by each function when system malfunction occurs.
 The adoption of the 4WD switch assembly (4WD sh ift switch and VDC OFF switch) enables to change the
control characteristics of the VDC function, the TCS function and the brake limited slip differential (BLSD)
function into an optimal characteristics, based on a st ate of the 4WD shift switch. (Models with 4WD system)
SYSTEM DIAGRAM
NOTE:
Transfer control unit is appli ed to models with 4WD system.
INPUT SIGNAL AND OUTPUT SIGNAL
Major signal transmission between each unit via communication lines is shown in the following table.
JPFIC0182GB
Component Signal description
Yaw rate/side/decel G sensor Mainly transmits the follo
wing signals to ABS actuator and elec tric unit (control unit) via com-
munication line
*1.
 Yaw rate signal
 Side G sensor signal
 Decel G sensor signal
ECM Mainly transmits the follo
wing signals to ABS actuator and elec tric unit (control unit) via CAN
communication.
 Accelerator pedal position signal
 Engine speed signal
Mainly receives the following si gnals from ABS actuator and electr ic unit (control unit) via CAN
communication.
 Target throttle position signal
Revision: 2010 May2011 QX56

SYSTEMBRC-17
< SYSTEM DESCRIPTION > [WITH VDC]
C
D
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G H
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M A
B
BRC
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O P*1: Communication line between yaw rate/side/decal G s ensor and ABS actuator and electric unit (control unit)
*2: Models with 4WD system
VALVE OPERATION
Each valve is operated and fluid pressure of brake caliper is controlled.
When Ordinary Brake is Applied
NOTE:
Control pressure sensor is applied to model s with Advanced Driver Assistance System.
TCMMainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN
communication.
 Shift position signal
 Current gear position signal
Transfer control unit
*2Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN
communication.
 Current 4WD mode 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 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
Component Signal description
Name Not activated When depressing brake pedal
Cut valve 1 Power supply is not supplied (open) Power supply is not supplied (open)
Cut valve 2 Power supply is not supplied (open) Power supply is not supplied (open)
Suction valve 1 Power supply is not supplied (close) Power supply is not supplied (close)
Suction valve 2 Power supply is not supplied (close) Power supply is not supplied (close)
JPFIC0150GB
Revision: 2010 May2011 QX56

BRC-18
< SYSTEM DESCRIPTION >[WITH VDC]
SYSTEM
Front RH caliper
 Pressurized brake fluid from accumulator is supplied
to front RH caliper through master cylinder part, cut
valve 1 and ABS IN valve.
Front LH caliper
 Pressurized brake fluid from accumulator is supplied to front LH caliper through master cylinder part, cut
valve 1 and ABS IN valve.
Rear RH caliper
 Pressurized brake fluid from accumulator is supplied to rear RH caliper through master cylinder part, cut
valve 2 and ABS IN valve.
Rear LH caliper
 Pressurized brake fluid from accumulator is supplied to rear LH caliper through master cylinder part, cut
valve 2 and ABS IN valve.
ABS is Operation (When Pressure Increases)
NOTE:
Control pressure sensor is applied to m odels with Advanced Driver Assistance System.
ABS IN valve Power supply is not supplied (open) Power supply is not supplied (open)
ABS OUT valve Power supply is not supplied (close) Power supply is not supplied (close)
Each caliper (fluid pressure) — Pressure increasesName Not activated When depressing brake pedal
Name Not activated When Pressure Increases
Cut valve 1 Power supply is not supplied (open) Power supply is supplied (close)
Cut valve 2 Power supply is not supplied (open) Power supply is not supplied (open)
Suction valve 1 Power supply is not supplied (close) Power supply is supplied (open)
Suction valve 2 Power supply is not supplied (close) Power supply is not supplied (close)
ABS IN valve Power supply is not supplied (open) Power supply is not supplied (open)
JPFIC0153GB
Revision: 2010 May2011 QX56

SYSTEMBRC-19
< SYSTEM DESCRIPTION > [WITH VDC]
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M A
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BRC
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Front RH caliper
 Pressurized brake fluid from accumulator is supplied to front RH caliper through master cylinder part, cut
valve 2, suction valve 1 and ABS IN valve.
Front LH caliper
 Pressurized brake fluid from accumulator is supplied to front LH caliper through master cylinder part, cut
valve 2, suction valve 1 and ABS IN valve.
Rear RH caliper
 Pressurized brake fluid from accumulator is supplied to rear RH caliper through master cylinder part, cut valve 2 and ABS IN valve.
Rear LH caliper
 Pressurized brake fluid from accumulator is supplied to rear LH caliper through master cylinder part, cut
valve 2 and ABS IN valve.
ABS is Operation (Whe n Pressure Holds)
NOTE:
Control pressure sensor is applied to model s with Advanced Driver Assistance System.
ABS OUT valve Power supp ly is not supplied (close) Power supply is not supplied (close)
Each caliper (fluid pressure) — Pressure increases Name Not activated When Pressure Increases
Name Not activated When Pressure Increases
Cut valve 1 Power supply is not supplied (open) Power supply is supplied (close)
Cut valve 2 Power supply is not supplied (open) Power supply is not supplied (open)
Suction valve 1 Power supply is not supplied (close) Power supply is supplied (open)
Suction valve 2 Power supply is not supplied (close) Power supply is not supplied (close)
ABS IN valve Power supp ly is not supplied (open) Power supply is supplied (close)
ABS OUT valve Power supp ly is not supplied (close) Power supply is not supplied (close)
Each caliper (fluid pressure) — Pressure holds
JPFIC0179GB
Revision: 2010 May2011 QX56

BRC-20
< SYSTEM DESCRIPTION >[WITH VDC]
SYSTEM
Front RH caliper ABS IN valve is close, fluid pressure of front RH caliper is holds.
Front LH caliper ABS IN valve is close, fluid pressure of front LH caliper is holds.
Rear RH caliper
 ABS IN valve is close and fluid pressure of rear RH caliper is holds.
Rear LH caliper ABS IN valve is close and fluid pressure of rear LH caliper is holds.
ABS is Operation (When
Pressure Decreases)
NOTE:
Control pressure sensor is applied to m odels with Advanced Driver Assistance System.
Front RH caliper Being returned to reservoir tank through ABS OUT valve, fluid pressure of front RH caliper is decreased.
Front LH caliper
 Being returned to reservoir tank through ABS OUT valve, fluid pressure of front LH caliper is decreased.
Rear RH caliper Being returned to reservoir tank through ABS OUT valve, fluid pressure of rear RH caliper is decreased.
Rear LH caliper
Name Not activated When pressure decreases
Cut valve 1 Power supply is not supplied (open) Power supply is supplied (close)
Cut valve 2 Power supply is not supplied (open) Power supply is not supplied (open)
Suction valve 1 Power supply is not supplied (close) Power supply is supplied (open)
Suction valve 2 Power supply is not supplied (close) Power supply is not supplied (close)
ABS IN valve Power supply is not supplied (open) Power supply is supplied (close)
ABS OUT valve Power supply is not supplied (close) Power supply is supplied (open)
Each caliper (fluid pres sure) — Pressure decreases
JPFIC0152GB
Revision: 2010 May2011 QX56

SYSTEMBRC-21
< SYSTEM DESCRIPTION > [WITH VDC]
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BRC
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 Being returned to reservoir tank through ABS OUT valve, fluid pressure of rear LH caliper is decreased.
VDC is Operation (When Pressure Increases)
NOTE:
Control pressure sensor is applied to models with Advanced Driver Assistance System.
Example: When other than rear LH wheel is operation in the figure.
Front RH caliper Pressurized brake fluid from accumulator is supplied to front RH caliper through suction valve 2, suction
valve 1 and ABS IN valve. When not increases, ABS IN valve is closed and brakes fluid is not supplied to
front RH caliper.
Front LH caliper
 Pressurized brake fluid from accumulator is supplied to front LH caliper through suction valve 2, suction
valve 1 and ABS IN valve. When not increases, ABS IN valve is closed and brakes fluid is not supplied to
front LH caliper.
Rear RH caliper
Name Not activated When Pressure Increases
Cut valve 1 Power supply is not supplied (open) Power supply is supplied (close)
Cut valve 2 Power supply is not supplied (open) Power supply is supplied (close)
Suction valve 1 Power supply is not supplied (close) Power supply is supplied (open)
Suction valve 2 Power supply is not supplied (close) Power supply is supplied (open)
ABS IN valve Power supply is not supplied (open) Only wheel that the pressure is to be in-
creased: Power supply is not supplied (open)
Wheel other than the one that the pressure
is to be increased: Power supply is supplied (close)
ABS OUT valve Power supp ly is not supplied (close) Power supply is not supplied (close)
Each caliper (fluid pressure) — Pressure increases (only wheel that the
pressure is to be increased)
JPFIC0154GB
Revision: 2010 May2011 QX56

BRC-22
< SYSTEM DESCRIPTION >[WITH VDC]
SYSTEM
 Pressurized brake fluid from accumulator is supplied to rear RH caliper through suction valve 2 and ABS IN
valve. When not increases, ABS IN valve is closed and brakes fluid is not supplied to rear RH caliper.
Rear LH caliper Pressurized brake fluid from accumulator is supplied to rear LH caliper through suction valve 2 and ABS IN
valve. When not increases, ABS IN va lve is closed and brakes fluid is not supplied to rear LH caliper.
VDC is Operation (When Pressure Holds)
NOTE:
Control pressure sensor is applied to m odels with Advanced Driver Assistance System.
Example: When other than front LH wheel is operation in the figure.
Front RH caliper ABS IN valve is close, fluid pressure of front RH caliper is holds.
Front LH caliper
 ABS IN valve is close, fluid pressure of front LH caliper is holds.
Rear RH caliper
 ABS IN valve is close, fluid pressure of rear RH caliper is holds.
Name Not activated When Pressure holds
Cut valve 1 Power supply is not supplied (open) Power supply is supplied (close)
Cut valve 2 Power supply is not supplied (open) Power supply is supplied (close)
Suction valve 1 Power supply is not supplied (close) Power supply is supplied (open)
Suction valve 2 Power supply is not supplied (close) Power supply is supplied (open)
ABS IN valve Power supply is not supplied (open) Only wheel that the pressure is to be holds:
Power supply is supplied (close)
Wheel other than the one that the pressure
is to be holds: Power supply is not supplied (open)
ABS OUT valve Power supply is not supplied (close) Power supply is not supplied (close)
Each caliper (f luid pressure) — Pressure holds (only wheel that the pres-
sure is to be holds)
JPFIC0180GB
Revision: 2010 May2011 QX56

SYSTEMBRC-23
< SYSTEM DESCRIPTION > [WITH VDC]
C
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G H
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M A
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BRC
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Rear LH caliper ABS IN valve is close, fluid pressure of rear LH caliper is holds.
VDC is Operation (When Pressure Decreases)
NOTE:
Control pressure sensor is applied to model s with Advanced Driver Assistance System.
Example: When other than front LH wheel is operation in the figure.
Front RH caliper Being returned to reservoir tank through ABS OUT valv e, fluid pressure of front RH caliper is decreased.
Front LH caliper
 Being returned to reservoir tank through ABS OUT valve, fluid pressure of front LH caliper is decreased.
Rear RH caliper
 Being returned to reservoir tank through ABS OUT valve, fluid pressure of rear RH caliper is decreased.
Name Not activated When pressure decreases
Cut valve 1 Power supply is not supplied (open) Power supply is supplied (close)
Cut valve 2 Power supply is not supplied (open) Power supply is supplied (close)
Suction valve 1 Power supply is not supplied (close) Power supply is supplied (open)
Suction valve 2 Power supply is not supplied (close) Power supply is supplied (open)
ABS IN valve Power supply is not supplied (open) Only wheel that the pressure is to be de-
creases: Power supply is supplied (close)
Wheel other than the one that the pressure
is to be decreases: Power supply is not supplied (open)
ABS OUT valve Power supply is not supplied (close) Only wheel that the pressure is to be de-
creases: Power supply is supplied (open)
Wheel other than the one that the pressure is to be decreases: Power supply is not supplied (close)
Each caliper (fluid pressure) — Pressure decreases (only wheel that the
pressure is to be decreases)
JPFIC0181GB
Revision: 2010 May2011 QX56