light INFINITI QX56 2011 Factory Workshop Manual

FRONT DISC BRAKEBR-39
< REMOVAL AND INSTALLATION >
C
DE
G H
I
J
K L
M A
B
BR
N
O P
2. Apply rubber grease to piston seals (1), and install them to cali- per.
CAUTION:
Never reuse piston seals.
3. Apply rubber grease to piston boots (1). Cover the piston (2) end with piston boot, and then install cylinder side lip on piston boots
securely into a groove on cylinder body.
CAUTION:
Never reuse piston boots.
4. Apply new brake fluid to pistons (1). Push piston into cylinder body by hand and push piston boots (2) piston-side lip into the
piston groove.
CAUTION:
Press the pistons evenly and var y the pressing point to pre-
vent cylinder inner wall from being rubbed.
5. Apply rubber grease to sliding pin boots, and install sliding pin boots to torque member.
6. Apply rubber grease to sliding pin, and install the cylinder body.
7. Install sliding pin bolts and tighten it to the specified torque. Refer to BR-34, "
BRAKE PAD : Exploded View".
BRAKE CALIPER ASSEMBLY : InspectionINFOID:0000000006222494
INSPECTION AFTER DISASSEMBLY
Check the following items and replace if necessary.
Cylinder Body
Check the cylinder inner wall for rust, wear, cracks or damage.
CAUTION:
Always clean with new brake fluid. Never clean wit h mineral oil such as gasoline and light oil.
Torque Member
Check the torque member for rust, wear, cracks or damage.
Pistons
Check the surface of the piston for rust, wear, cracks or damage.
CAUTION:
A piston sliding surface is plat ed. Never polish with sandpaper.
Sliding Pin and Sliding Pin Boot
Check the sliding pins and sliding pin boots for rust, wear, cracks or damage.
INSPECTION AFTER INSTALLATION
1. Check a drag of front disc brake. If any dr ag is found, follow the procedure described below.
2. Remove brake pads. Refer to BR-34, "
BRAKE PAD : Removal and Installation".
JPFIA0032ZZ
JPFIA0782ZZ
JPFIA0034ZZ
Revision: 2010 May2011 QX56

BR-46
< REMOVAL AND INSTALLATION >
REAR DISC BRAKE
CAUTION:
Always clean with new brake fluid. Never clean with mineral oil such as gasoline and light oil.
Torque Member
Check the torque member for rust, wear, cracks or damage.
Piston
Check the surface of the piston for rust, wear, cracks or damage.
CAUTION:
A piston sliding surface is plat ed. Never polish with sandpaper.
Sliding Pin, Sliding Pin Boot and Bushing
Check the sliding pins, sliding pin boots and bushing for rust, wear, cracks or damage.
INSPECTION AFTER INSTALLATION
1. Check a drag of rear disc brake. If any dr ag is found, follow the procedure described below.
2. Remove brake pads. Refer to BR-41, "
BRAKE PAD : Removal and Installation".
3. Press the piston. Refer to BR-41, "
BRAKE PAD : Removal and Installation".
4. Install brake pads. Refer to BR-41, "
BRAKE PAD : Removal and Installation".
5. Depress the brake pedal several times.
6. Check a drag of rear disc brake again. If any drag is found, disassemble the caliper. Refer to BR-44,
"BRAKE CALIPER ASSEMBLY : Disassembly and Assembly".
7. Burnish contact surfaces brake pads and disc rotor after refinishing or replacing disc rotor, or if a soft pedal occurs at very low mileage. Refer to BR-18, "
DISC ROTOR : Inspection and Adjustment".
Revision: 2010 May2011 QX56

BRC-6
< PRECAUTION >[WITH VDC]
PRECAUTIONS
5. When the repair work is completed, re-connect bot
h battery cables. With the brake pedal released, turn
the push-button ignition switch from ACC position to ON position, then to LOCK position. (The steering
wheel will lock when the push-button igniti on switch is turned to LOCK position.)
6. Perform self-diagnosis check of all control units using CONSULT-III.
Precaution for Procedure without Cowl Top CoverINFOID:0000000006228176
When performing the procedure after removing cowl top cover, cover
the lower end of windshield with urethane, etc.
Precaution for Brake SystemINFOID:0000000006222556
WARNING:
Clean any dust from the front brake and rear brake using a vacuum dust collector. Never blow by com-
pressed air.
 Brake fluid use refer to MA-10, "
Fluids and Lubricants".
 Never reuse drained brake fluid.
 Never spill or splash brake fluid on painted surfaces. Brake fluid may seriously damage paint. Wipe it off
immediately and wash with water if it gets on a painted surface.
 Always confirm the specified tightening torque when installing the brake pipes.
 After pressing the brake pedal more deeply or harder t han normal driving, such as air bleeding, check each
item of brake pedal. Adjust brake pedal if it is outside the standard value.
 Never use mineral oils such as gasoline or light oil to clean. They may damage rubber parts and cause
improper operation.
 Always loosen the brake tube flar e nut with a flare nut wrench.
 Tighten the brake tube flare nut to the specified torque with a crow-
foot (A) and torque wrench (B).
 Always connect the battery terminal when moving the vehicle.
 Turn the ignition switch OFF and disconnect the ABS actuator and
electric unit (control unit) harness connector or the battery negative
terminal before performing the work.
 Check that no brake fluid leakage is present after replacing the parts.
Precaution for Brak e Control SystemINFOID:0000000006222557
 Slight vibrations are felt on the brake pedal and the operation noises occur, when VDC function, TCS func-
tion, ABS function, EBD function, hill start assist function or brake limited slip differential (BLSD) function
operates. This is not a malfunction because it is caus ed by VDC function, TCS function, ABS function, EBD
function, hill start assist function or brake limited sl ip differential (BLSD) function that is normally operated.
 When starting engine or when starting vehicle just after starting engine, brake pedal may vibrate or motor
operating noise may be heard from engine compartment. This is normal condition.
 Brake stopping distance may become longer than models without ABS function depending on the road con-
ditions, when ABS function is operated on slippery r oad like rough road, gravel road or snowy road.
 When a malfunction is indicated, always collect info rmation from the customer about conditions of occur-
rence, estimate cause and perform operation. Check brake booster operation, brake fluid level and brake
fluid leakage, as well as electrical system.
 The optimum performance is achieved by control for V DC function, TCS function, ABS function, EBD func-
tion, hill start assist function or brake limited slip di fferential (BLSD) function when all of brakes, suspensions
PIIB3706J
JPFIA0001ZZ
Revision: 2010 May2011 QX56

SYSTEMBRC-29
< SYSTEM DESCRIPTION > [WITH VDC]
C
D
E
G H
I
J
K L
M A
B
BRC
N
O P
side/decel G- sensor and wheel sensor, vehicle drivi ng conditions (conditions of understeer or oversteer) are
judged and vehicle stability is improved by brake forc e control on all 4 wheels and engine output control.
 Control unit portion automatically improves driving st ability by performing brake force control as well as
engine output control, by transmitting drive signal to actuator portion according to difference between target
side slip amount and vehicle side slip amount
 VDC function can be switched to non-operational status (OFF) by operating VDC OFF switch. In this case,
VDC OFF indicator lamp turns ON.
 VDC function is not operate when 4WD mode is “4L”. (Models with 4WD system)
 VDC warning lamp blinking while VDC function is in oper ation and indicates to the driver that the function is
in operation.
 Slight vibrations are felt on the brake pedal and t he operation noises occur, when VDC function operates.
This is not a malfunction because it is caus ed by VDC function that is normally operated.
 CONSULT-III can be used to diagnose the system diagnosis.
 Fail-safe function is adopted. When a malfunction occurs in VDC function, the control is suspended for VDC
function, TCS function, hill start as sist function and brake limited slip di fferential (BLSD) function. The vehi-
cle status becomes the same as m odels without VDC function, TCS functi on, hill start assist function and
brake limited slip differential (BLSD) function. Ho wever, ABS function and EBD function are operated nor-
mally. Refer to BRC-25, "
Fail-safe".
NOTE:
VDC has the characteristic as de scribed here, but it is not the device that helps reckless driving.
SYSTEM DIAGRAM
NOTE:
Transfer control unit is applied to models with 4WD system.
INPUT SIGNAL AND OUTPUT SIGNAL
JPFIC0133GB
JPFIC0183GB
Revision: 2010 May2011 QX56

SYSTEMBRC-31
< SYSTEM DESCRIPTION > [WITH VDC]
C
D
E
G H
I
J
K L
M A
B
BRC
N
O P
 During a cornering, brake force (brake fluid pressu re) is applied on front wheel and rear wheel on the inner
side of turn. Moment directing towards the inner side of turn is generated. Understeer is prevented.
 Applying braking during a cornering on a slippery road, when understeer tendency is judged large, engine
output is controlled as well as brake force (brake fluid pressure) of four wheels. Understeer tendency
decreases.
TCS FUNCTION
TCS FUNCTION : System DescriptionINFOID:0000000006222573
 Wheel spin status of drive wheel is detected by wheel sensor of 4
wheels. Engine output and transmission shift status is controlled
so that slip rate of drive wheels is in appropriate level. When wheel
spin occurs on drive wheel, ABS ac tuator and electric unit (control
unit) perform brake force control of LH and RH drive wheels (apply
brake force by increasing brake fluid pressure of drive wheel) and
decrease engine torque by engine torque control. Wheel spin
amount decreases. Engine torque is controlled to appropriate
level.
 TCS function can be switched to non-operational status (OFF) by
operating VDC OFF switch. In this case, VDC OFF indicator lamp
turns ON.
 TCS function is not operate when 4WD mode is “4L”. (Models with
4WD system)
 VDC warning lamp blinking while TCS function is in operation and indicates to the driver that the function is in operation.
 Slight vibrations are felt on the brake pedal and the operation noises occur, when TCS function operates. This is not a malfunc-
tion because it is caused by TCS function that is normally oper-
ated.
 CONSULT-III can be used to diagnose the system diagnosis.
 Fail-safe function is adopted. W hen a malfunction occurs in TCS
function, the control is suspended for VDC function, TCS function,
hill start assist function and brake limited slip differential (BLSD)
function. The vehicle status becomes the same as models without VDC function, TCS function, hill start
assist function and brake limited slip differential (B LSD) function. However, ABS function and EBD function
are operated normally. Refer to BRC-25, "
Fail-safe".
SYSTEM DIAGRAM
NOTE:
JPFIC0137GB
JPFIC0138GB
JPFIC0139GB
Revision: 2010 May2011 QX56

SYSTEMBRC-33
< SYSTEM DESCRIPTION > [WITH VDC]
C
D
E
G H
I
J
K L
M A
B
BRC
N
O P
ABS FUNCTION : System DescriptionINFOID:0000000006222574
 By preventing wheel lock through brake force (brake flui d pressure) control that is electronically controlled by
detecting wheel speed during braking, stability during em ergency braking is improved so that obstacles can
be easily bypassed by steering operation.
 During braking, control units calculates 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 tendencie s are moderated during brak-
ing 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 oper ates. This is not a malfunc-
tion because it is caused by ABS function that is normally oper-
ated.
 CONSULT-III 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, TCS function,
hill start assist function and brake limited slip differential (BLSD)
function. The vehicle status becomes the same as models without
VDC function, TCS function, ABS func tion, hill start assist function
and brake limited slip differential (BLSD) function. However, EBD
function is operated normally. Refer to BRC-25, "
Fail-safe".
NOTE:
 ABS has the characteristic as described here, but it is not the device that helps reckless driving.
 To stop vehicle efficiently, ABS does not operate and ordinary brake operates at low speed [approx. 5 to 10 km/h (3.1 to 6.2
MPH) or less, but differs subject to road conditions).
 Self-diagnosis is performed immediately after when engine starts and when vehicle initially is driven [by vehi-
cle speed approx. 15 km/h (9.3 MPH)]. Motor sounds are generated during self-diagnosis. In addition, brake
pedal may be felt heavy when depressing brake pedal lightly. These symptoms are not malfunctions.
SYSTEM DIAGRAM
NOTE:
JPFIC0140GB
Revision: 2010 May2011 QX56

BRC-34
< SYSTEM DESCRIPTION >[WITH VDC]
SYSTEM
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.
*1: Communication line between yaw rate/side/decal G s ensor and ABS actuator and electric unit (control unit)
*2: Models with 4WD system
EBD FUNCTION
EBD FUNCTION : System DescriptionINFOID:0000000006222575
 By preventing rear wheel slip increase through rear wheel brake force (brake fluid pressure) control that is
electronically controlled when slight skip on front and r ear wheels are detected during braking, stability dur-
ing braking is improved.
JPFIC0184GB
Component Signal description
Yaw rate/side/decel G sensor Mainly transmits the following si
gnals to ABS actuator and electric unit (control unit) via com-
munication line
*1.
 Yaw rate signal
 Side G sensor signal
 Decel G sensor signal
Transfer control unit
*2Mainly transmits the following si gnals to ABS actuator and electric unit (control unit) via CAN
communication.
 Current 4WD mode signal
Combination meter Mainly receives
the following signals from ABS actuator and electric unit (control unit) via CAN
communication.
 ABS warning lamp signal
Revision: 2010 May2011 QX56

SYSTEMBRC-35
< SYSTEM DESCRIPTION > [WITH VDC]
C
D
E
G H
I
J
K L
M A
B
BRC
N
O P
 EBD function is expanded and developed from conventi onal ABS function and corrects rear wheel brake
force to appropriate level by electronic control according to load weight (number of passengers).
 During braking, control unit portion compares slight slip on front and rear wheels by wheel speed sensor signal, transmits drive sig-
nal to actuator portion when rear wheel slip exceeds front wheel
slip for the specified value or more, and controls rear wheel brake
force (brake fluid pressure) so t hat increase of rear wheel slip is
prevented and slips on front wheel and rear wheel are nearly
equalized. ABS control is applied when slip on each wheel
increases and wheel speed is the threshold value of ABS control or
less.
 CONSULT-III can be used to diagnose the system diagnosis.
 Fail-safe function is adopted. When a malfunction occurs in EBD function, the control is suspended for VDC function, TCS function,
ABS function, EBD function, hill start assist function and brake lim-
ited slip differential (BLSD) func tion. The vehicle status becomes
the same as models without VDC function, TCS function, ABS
function, EBD function, hill start assist function and brake limited
slip differential (BLSD) function. Refer to BRC-25, "
Fail-safe".
JPFIC0142GB
JPFIC0143GB
Revision: 2010 May2011 QX56

BRC-38
< SYSTEM DESCRIPTION >[WITH VDC]
SYSTEM
 Brake limited slip differential (BLSD) function operates
while VDC function is in non-operational status (OFF)
by VDC OFF switch.
 VDC warning lamp blinking while brake limited slip di fferential (BLSD) function is in operation and indicates
to the driver that the function is in operation.
 Slight vibrations are felt on the brake pedal and the operation noises occur, when brake limited slip differen-
tial (BLSD) function operates. This is not a malfunction because it is caused by brake limited slip differential
(BLSD) function that is normally operated.
 Fail-safe function is adopted. When a malfunction occurs in brake limited slip differential (BLSD) function,
the control is suspended for VDC function, TCS function, hi ll start assist function and brake limited slip differ-
ential (BLSD) function. The vehicle status becomes the same as models without VDC function, TCS func-
tion, hill start assist function and brake limited slip di fferential (BLSD) function. However, ABS function and
EBD function are operated normally. Refer to BRC-25, "
Fail-safe".
SYSTEM DIAGRAM
NOTE:
Transfer control unit is applied 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.
JPFIC0183GB
Component Signal description
Yaw rate/side/decel G sensor Mainly transmits the following si
gnals to ABS actuator and electric unit (control unit) via com-
munication line
*1.
 Yaw rate signal
 Side G sensor signal
 Decel G sensor signal
ECM Mainly transmits the following si
gnals 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 si
gnals to ABS actuator and electric unit (control unit) via CAN
communication.
 Shift position signal
Revision: 2010 May2011 QX56

BRAKE PEDAL VIBRATION OR OPERATION SOUND OCCURS
BRC-131
< SYMPTOM DIAGNOSIS > [WITH VDC]
C
D
E
G H
I
J
K L
M A
B
BRC
N
O P
BRAKE PEDAL VIBRATION OR OPERATION SOUND OCCURS
DescriptionINFOID:0000000006222665
 Brake pedal vibrates and motor sound from ABS actuat or and electric unit (control unit) occurs, when the
engine starts.
 Brake pedal vibrates during braking.
CAUTION:
Vibration may be felt during brake pedal is lightly de pressed (just placing a foot on it) in the following
conditions. This is normal.
 When shifting gears
 When driving on slippery road
 During cornering at high speed
 When passing over bumps or grooves [Approx. 50 mm (1.97 in) or more]
 When pulling away just after starting engine [at approx. 10 km/h (6.2 MPH) or higher]
Diagnosis ProcedureINFOID:0000000006222666
1.CHECK SYMPTON 1
Depress the brake pedal 10 times or more with the engine stopped and decrease the accumulator pressure to
check that there are pedal vibrations when the engine is started.
Do vibrations occur?
YES >> GO TO 2.
NO >> Check brake pedal. Refer to BR-21, "
Inspection and Adjustment".
2.CHECK SYMPTON 2
Depress the brake pedal 10 times or more with the engine stopped and decrease the accumulator pressure to
check that motor noise from ABS actuator and electr ic unit (control unit) occurs when the engine starts.
Does the operation sound occur?
YES >> GO TO 3.
NO >> Perform self-diagnosis for “ABS” with CONSULT-III.
3.CHECK SYMPTON 3
Check symptoms when electrical component (headlamps, etc.) switches are operated.
Does the symptom occur?
YES >> Check that radio (including wiring), antenna and antenna lead-in wires are not located near ABS actuator and electric unit (control unit). Move them if they are located near ABS actuator and elec-
tric unit (control unit).
NO >> Normal
Revision: 2010 May2011 QX56