2011 INFINITI QX56 ABS

THE BRAKING DISTANCE IS LONGBRC-129
< SYMPTOM DIAGNOSIS > [WITH VDC]
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THE BRAKING DISTANCE IS LONG
DescriptionINFOID:0000000006222661
Brake stopping distance is long when ABS function is operated.
Diagnosis ProcedureINFOID:0000000006222662
CAUTION:
Brake stopping distance on slippery road like roug h road, gravel road or snowy road may become
longer when ABS is operated than when ABS is not operated.
1.CHECK BRAKING FORCE
Check brake force using a brake tester.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Check each component s of brake system.
2.CHECK BRAKE PERFORMANCE
Disconnect ABS actuator and electric unit (control unit) connector so that ABS does not operate. Check brake
stopping distance in this condition. Connect harness connectors after checking.
Is the inspection result normal?
YES >> Normal
NO >> Check each component s of brake system.
Revision: 2010 May2011 QX56

BRC-130
< SYMPTOM DIAGNOSIS >[WITH VDC]
DOES NOT OPERATE
DOES NOT OPERATE
DescriptionINFOID:0000000006222663
VDC function, TCS function, ABS functi
on, EBD function, hill start assist function and brake limited slip differ-
ential (BLSD) function does not operate.
Diagnosis ProcedureINFOID:0000000006222664
CAUTION:
 VDC function, ABS function and EBD function never operate when the vehicle speed is 10 km/h (6.2
MPH) or less.
 TCS function, hill start assist fu nction and brake limited slip diffe rential (BLSD) function operates
when the vehicle speed is 0 km/h (0 MPH) (the vehicle is in stop status).
 VDC function and TCS function never operate wh en VDC OFF switch is operated (when VDC OFF
indicator lamp turns ON).
1.CHECK ABS WARNING LAMP
Check that ABS warning lamp, brake warning lamp and VDC warning lamp turn ON and turn OFF approx. 1
second after key switch is turned ON. Check that ABS warning lamp, brake warning lamp and VDC warning
lamp and stay in OFF status during driving.
CAUTION:
Brake warning lamp turns ON when parking brake is operated (parking brake switch is ON) or brake
fluid is less than the specified level (brake fluid level switch is ON).
Is the inspection result normal?
YES >> Normal
NO >> Perform self-diagnosis for “ABS” with CONSULT-III.
Revision: 2010 May2011 QX56

BRAKE PEDAL VIBRATION OR OPERATION SOUND OCCURS
BRC-131
< SYMPTOM DIAGNOSIS > [WITH VDC]
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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

BRC-132
< SYMPTOM DIAGNOSIS >[WITH VDC]
VEHICLE JERKS DURING
VEHICLE JERKS DURING
DescriptionINFOID:0000000006222667
The vehicle jerks when VDC function, TCS function, ABS
function, EBD function, hill start assist function and
brake limited slip differential (BLSD) function operates.
Diagnosis ProcedureINFOID:0000000006222668
1.CHECK SYMPTOM
Check that the vehicle jerks when VDC function, TCS f unction, ABS function, EBD function, hill start assist
function and brake limited slip differential (BLSD) function operates.
Is the inspection result normal?
YES >> Normal
NO >> GO TO 2.
2.PERFORM THE SELF-DIAGNOSIS
With CONSULT-III.
Perform self-diagnosis for “ABS”.
Is any DTC detected?
YES >> Check the DTC. Refer to BRC-51, "DTC Index".
NO >> GO TO 3.
3.CHECK CONNECTOR
With CONSULT-III.
1. Turn the ignition switch OFF.
2. Disconnect ABS actuator and electric unit (control unit) harness connector.
3. Check connector terminal for deformation, disconnection and looseness.
4. Connect harness connector and perform self-diagnosis for “ABS” again.
Is the inspection result normal?
YES >> GO TO 4.
NO >> Poor connection of connector terminal. Repair or replace connector terminal.
4.CHECK ECM AND TCM SELF-DIAGNOSIS RESULTS
With CONSULT-III.
Perform self-diagnosis for “E NGINE” and “TRANSMISSION”.
Is any DTC detected?
YES >> Check the DTC.
NO >> Replace ABS actuator and electric unit (control unit). Refer to BRC-137, "
Removal and Installa-
tion".
Revision: 2010 May2011 QX56

NORMAL OPERATING CONDITIONBRC-133
< SYMPTOM DIAGNOSIS > [WITH VDC]
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NORMAL OPERATING CONDITION
DescriptionINFOID:0000000006222669
Symptom Result
Brake pedal slightly vibrates and operation sound (motor sound and sound from suspen-
sion) occurs when VDC function, TCS function, ABS function, EBD function, hill start assist
function and brake limited slip differential (BLSD) function operates. This is not a malfunction, The symptom
occurs VDC function
, TCS function, ABS
function, EBD function, hill start assist
function and brake limited slip differential
(BLSD) function that are normally operat-
ed.
Brake stopping distance may become longer than models without ABS function depending
on the road conditions, when
ABS function is operated on slip pery road like rough road,
gravel road or snowy road.
Brake pedal vibrates and operation sound occurs during sudden acceleration and corner-
ing, when VDC function, TCS function, hill start assist function and brake limited slip differ-
ential (BLSD) function is operated.
Brake pedal vibrates and motor sound from the engine room occurs, when the engine starts
or the vehicle starts just after starting the engine This is not a malfunction. The symptom
occurs during the brake fluid accumula-
tion in the accumulator and operational
check of the ABS actuator and electric
unit (control unit).
Acceleration may be felt insufficient depending on the road conditions. This is not a malfunction. The symptom occurs TCS function that puts the highest
priority to obtain the optimum traction
(stability).
TCS may operate momentarily, while driving on a road where friction coefficient varies, or
when downshifting or fully depressing accelerator pedal
ABS warning lamp and VDC warning lamp may turn ON, when the vehicle is on a rotating
turntable or is given a strong shaking or large vibrations on a ship while the engine is run-
ning.
In this case, restart the engine on a nor-
mal road. If the normal condition is re-
stored, there is no malfunction. In that
case, erase self-diagnosis result memory
for “ABS” with CONSULT-III.
VDC warning lamp may turn ON and VDC function, TCS function, hill start assist function
and brake limited slip differential (BLSD) function may not normally operate, when driving
on a special road the is extremely slanted (bank in a circuit course).
A malfunction in yaw rate/side/decel G sensor system may be detected when the vehicle
sharply turns during a spin turn, acceleration turn or drift driving while VDC function and
TCS function are OFF (VDC OFF switch is pressed and VDC OFF indicator lamp is in ON
status).
The vehicle speed does not increase, when the accelerator pedal is depressed while the
vehicle is on a 2-wheel chassis dynamometer for speedometer check.
This is not malfunction. (When checking
the vehicle on a chassis dynamometer,
operate VDC OFF switch so that TCS
function is OFF.)
The VDC warning lamp, ABS warn ing lamp and brake warning lamp turn ON and DTC
“C118E” may be detected in self-diagnosis resu lt of “ABS” when the brake pedal is exces-
sively operated, such as air bleeding. This is not a system malfunction because
this occurs due to the temporary de-
crease in accumulator fluid pressure. The
system returns to no
rmal condition when
the accumulator fluid pressure reaches
the specified pressure with the ignition
switch ON and the VDC warning lamp,
ABS warning lamp, a nd brake warning
lamp turn OFF. After these steps, ABS
self-diagnosis results are erased.
VDC OFF indicator lamp turns ON and TCS function is not operate when 4WD mode is “4L”.
(Models with 4WD system) This is not a malfunction. When the 4WD
mode becomes “4L” state, the TCS func-
tion is disabled. This function is enabled
when the 4WD mode becomes “AUTO”
or “4H”.
Revision: 2010 May2011 QX56

ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)BRC-137
< REMOVAL AND INSTALLATION > [WITH VDC]
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ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)
Removal and InstallationINFOID:0000000006222676
REMOVAL
1. Remove hydraulic booster assembly. Refer to BR-29, "Removal and Installation".
CAUTION:
After replacing the hydraulic booster assembly or motor/accumulator assembly, always follow the
accumulator disposal procedure to discard the hydraulic booster assembly or motor/accumulator
assembly. Refer to BR-33, "
Disposal".
2. Remove ABS actuator and electric unit (control unit). Refer to BR-30, "
Disassembly and Assembly".
INSTALLATION
Note the following, and install in the reverse order of removal.
 When installing brake tube, tighten to the specified torque using a crowfoot and torque wrench so that flare
nut and brake tube are not damaged. Refer to BR-22, "
FRONT : Exploded View".
 Never remove and install hydraulic booster assembly by holding harness.
 Bleed air from brake piping after installation. Refer to BR-11, "
Bleeding Brake System".
 Never apply excessive impact to hydraulic booster assembly, such as by dropping it.
 Check that connector is fully locked after hydraul ic booster assembly harness connector is installed.
 Perform decel G sensor calibration when hydraulic boos ter assembly [ABS actuator and electric unit (control
unit)] is replaced. Refer to BRC-66, "
Work Procedure".
Revision: 2010 May2011 QX56

BRC-142
< SYSTEM DESCRIPTION >[BRAKE ASSIST (WITH PREVIEW FUNCTION)]
COMPONENT PARTS
SYSTEM DESCRIPTION
COMPONENT PARTS
Component Parts LocationINFOID:0000000006248456
1. ICC steering switch 2. Information display, ICC system
warning lamp, IBA OFF indicator
lamp, buzzer
(On the combination meter)3. BCM
Refer to BCS-4, "
BODY CONTROL
SYSTEM : Component Parts Loca-
tion"
4. Transfer control unit
Refer to DLN-10, "
Component Parts
Location"
5. ICC brake hold relay 6. ECM
Refer to EC-16, "
Component Parts
Location"
7. ICC sensor 8. TCM
Refer to TM-10, "
A/T CONTROL
SYSTEM : Component Parts Loca-
tion"
9. ABS actuator and el ectric unit (con-
trol unit)
Refer to BRC-10, "
Component Parts
Location"
10. Stop lamp switch 11. ICC brake switch 12. IBA OFF switch
JSOIA0362ZZ
Revision: 2010 May2011 QX56

COMPONENT PARTSBRC-143
< SYSTEM DESCRIPTION > [BRAKE ASSIST (WITH PREVIEW FUNCTION)]
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Component DescriptionINFOID:0000000006248457
× : Applicable
13. Steering angle sensor
Refer to BRC-10, "
Component Parts
Location"
14. ADAS control unit
Refer to DAS-13, "
Component Parts
Location"
A. Back side of engine room (RH) B. Front bumper (center) C. Upper side of brake pedal
D. Under side of instrument lower driver
panel
Component Function
Description
Vehicle-to-vehicle distance control mode
Conventional (fixed speed) cruise control mode Intelligent Brake Assist (IBA)
Brake Assist (with preview function)
ADAS control unit ×××× ADAS control unit calculates a target distance between vehicles
and a target speed, based on signals received from each sensor
and switch to transmit an engine torque command value to ECM
and a brake fluid pressure cont rol signal to ABS actuator and
electric unit (control unit) via CAN communication
 ADAS control unit transmits buzzer output signal to combination
meter via CAN communication
ICC sensor ×××× ICC sensor detects light reflected from a vehicle ahead by irra-
diating laser forward and calculates a distance from the vehicle
ahead and a relative speed, based on the detected signal
 ICC sensor transmits the presence/absence of vehicle ahead and the distance from the vehicle to ADAS control unit via ITS
communication
ECM ×××× ECM transmits the accelerator pedal position signal, ICC brake
switch signal, stop lamp switch signal, ICC steering switch sig-
nal, etc. to ADAS control unit via CAN communication
 ECM controls the electric throttle control actuator based on the engine torque demand received from the ADAS control unit via
CAN communication
ABS actuator and electric unit
(control unit) ×××× ABS actuator and electric unit (c
ontrol unit) transmits the vehicle
speed signal (wheel speed), stop lamp signal and VDC/TCS/
ABS system operation condition to ADAS control unit via CAN
communication
 ABS actuator and electric unit (c ontrol unit) controls the brake,
based on a brake fluid pressure control signal received from the
ADAS control unit via CAN communication
BCM ×BCM transmits the front wiper request signal to ADAS control unit
via CAN communication
TCM ××TCM transmits the signal related to A/T control to ADAS control
unit via CAN communication
Revision: 2010 May2011 QX56