2011 INFINITI QX56 ABS

BRC-1
BRAKES
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SECTION BRC
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BRC
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CONTENTS
BRAKE CONTROL SYSTEM
WITH VDC
PRECAUTION ................ ...............................
5
PRECAUTIONS .............................................. .....5
Precaution for Supplemental Restraint System
(SRS) "AIR BAG" and "SEAT BELT PRE-TEN-
SIONER" ............................................................. ......
5
Precaution Necessary for Steering Wheel Rota-
tion after Battery Disconnect .....................................
5
Precaution for Procedure without Cowl Top Cover ......6
Precaution for Brake System ....................................6
Precaution for Brake Control System ........................6
Precaution for Harness Repair ..................................7
PREPARATION ............................................9
PREPARATION .............................................. .....9
Commercial Service Tools .................................. ......9
SYSTEM DESCRIPTION .............................10
COMPONENT PARTS ................................... ....10
Component Parts Location .................................. ....10
Component Description ...........................................13
ABS Actuator and Electric Unit (Control Unit) .........14
Wheel Sensor and Sensor Rotor ............................14
Stop Lamp Switch ...................................................15
Steering Angle Sensor ............................................15
Yaw Rate/Side/Decel G sensor ...............................15
Brake Fluid Level Switch .........................................15
Parking Brake Switch ..............................................15
VDC OFF Switch .....................................................15
SYSTEM .............................................................16
System Description ............................................. ....16
Fail-safe ..................................................................25
Protection Function .................................................28
VDC FUNCTION .................................................... ....28
VDC FUNCTION : System Description ...................28
TCS FUNCTION ..................................................... ....31
TCS FUNCTION : System Description ....................31
ABS FUNCTION .................................................... ....32
ABS FUNCTION : System Description ....................33
EBD FUNCTION .................................................... ....34
EBD FUNCTION : System Description ....................34
HILL START ASSIST FUNCTION ......................... ....36
hill start assist FUNCTION : System Description ....36
BRAKE LIMITED SLIP DIFFERENTIAL (BLSD)
FUNCTION ............................................................. ....
37
BRAKE LIMITED SLIP DIFFERENTIAL (BLSD)
FUNCTION : System Description ............................
37
DIAGNOSIS SYSTEM [ABS ACTUATOR
AND ELECTRIC UNIT (CONTROL UNIT)] .......
40
CONSULT-III Function ............................................40
ECU DIAGNOSIS INFORMATION ..............45
ABS ACTUATOR AND ELECTRIC UNIT
(CONTROL UNIT) .............................................
45
Reference Value .................................................. ....45
Fail-safe ...................................................................47
Protection Function ..................................................50
DTC Inspection Priority Chart ..................................50
DTC Index ...............................................................51
WIRING DIAGRAM ......................................53
BRAKE CONTROL SYSTEM ...........................53
Wiring Diagram .................................................... ....53
BASIC INSPECTION ...................................60
DIAGNOSIS AND REPAIR WORK FLOW .......60
Work Flow ............................................................ ....60
Diagnostic Work Sheet ............................................61
Revision: 2010 May2011 QX56

BRC-2
ADDITIONAL SERVICE WHEN REPLACING
ABS ACTUATOR AND ELECTRIC UNIT
(CONTROL UNIT) ..............................................
63
Description ........................................................... ...63
ADJUSTMENT OF STEERING ANGLE SEN-
SOR NEUTRAL POSITION ...............................
64
Description ........................................................... ...64
Work Procedure ......................................................64
CALIBRATION OF DECEL G SENSOR ...........66
Description ........................................................... ...66
Work Procedure ......................................................66
DTC/CIRCUIT DIAGNOSIS ...................... ...68
C1101, C1102, C1103, C1104 WHEEL SEN-
SOR ................................................................. ...
68
DTC Logic ............................................................ ...68
Diagnosis Procedure ..............................................68
C1105, C1106, C1107, C1108 WHEEL SEN-
SOR ....................................................................
70
DTC Logic ............................................................ ...70
Diagnosis Procedure ..............................................70
C1109 POWER AND GROUND SYSTEM .........72
Description ........................................................... ...72
DTC Logic ...............................................................72
Diagnosis Procedure ..............................................72
C1111 PUMP MOTOR .......................................75
DTC Logic ............................................................ ...75
Diagnosis Procedure ..............................................75
C1115 WHEEL SENSOR ...................................77
DTC Logic ............................................................ ...77
Diagnosis Procedure ..............................................77
C1116 STOP LAMP SWITCH ............................79
DTC Logic ............................................................ ...79
Diagnosis Procedure ..............................................79
Component Inspection (Stop lamp Switch) ............85
Component Inspection (Stop Lamp Relay) .............86
C1118 TRANSFER CONTROL UNIT ................87
DTC Logic ............................................................ ...87
Diagnosis Procedure ..............................................87
C1120, C1122, C1124, C1126 ABS IN VALVE
SYSTEM .......................................................... ...
88
DTC Logic ............................................................ ...88
Diagnosis Procedure ..............................................88
C1121, C1123, C1125, C1127 ABS OUT
VALVE SYSTEM ................................................
90
DTC Logic ............................................................ ...90
Diagnosis Procedure ..............................................90
C1130 ENGINE SIGNAL ...................................92
DTC Logic ............................................................ ...92
Diagnosis Procedure ............................................ ...92
C1140 ACTUATOR RELAY SYSTEM ..............93
DTC Logic ............................................................ ...93
Diagnosis Procedure ...............................................93
C1142 PRESS SENSOR ...................................95
DTC Logic ............................................................ ...95
Diagnosis Procedure ...............................................95
C1143 STEERING ANGLE SENSOR ...............97
DTC Logic ............................................................ ...97
Diagnosis Procedure ...............................................97
C1144 INCOMPLETE STEERING ANGLE
SENSOR ADJUSTMENT ..................................
99
DTC Logic ............................................................ ...99
Diagnosis Procedure ...............................................99
C1145, C1146 YAW RATE/SIDE/DECEL G
SENSOR ...........................................................
100
DTC Logic ............................................................ .100
Diagnosis Procedure .............................................100
C1155 BRAKE FLUID LEVEL SWITCH ..........103
DTC Logic ............................................................ .103
Diagnosis Procedure .............................................103
Component Inspection ..........................................104
C1160 DECEL G SEN SET ..............................105
DTC Logic ............................................................ .105
Diagnosis Procedure .............................................105
C1164, C1165 CV SYSTEM .............................106
DTC Logic ............................................................ .106
Diagnosis Procedure .............................................106
C1166, C1167 SV SYSTEM .............................108
DTC Logic ............................................................ .108
Diagnosis Procedure .............................................108
C1170 VARIANT CODING ...............................110
DTC Logic ............................................................ .110
Diagnosis Procedure .............................................110
C118E ACCUMULATOR ..................................111
DTC Logic ............................................................ .111
Diagnosis Procedure .............................................111
U1000 CAN COMM CIRCUIT ...........................112
Description ........................................................... .112
DTC Logic .............................................................112
Diagnosis Procedure .............................................112
POWER SUPPLY AND GROUND CIRCUIT ....113
Description ........................................................... .113
Diagnosis Procedure .............................................113
PARKING BRAKE SWITCH .............................117
Component Function Check ................................ .117
Diagnosis Procedure .............................................117
Component Inspection ..........................................118
Revision: 2010 May2011 QX56

BRC-3
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VDC OFF SWITCH ......................................... ..119
Component Function Check ................................ ..119
Diagnosis Procedure .............................................119
Component Inspection ..........................................120
ABS WARNING LAMP ................................... ..122
Component Function Check ................................ ..122
Diagnosis Procedure .............................................122
BRAKE WARNING LAMP ...............................123
Component Function Check ................................ ..123
Diagnosis Procedure .............................................123
VDC WARNING LAMP .....................................125
Component Function Check ................................ ..125
Diagnosis Procedure .............................................125
VDC OFF INDICATOR LAMP ..........................126
Component Function Check ................................ ..126
Diagnosis Procedure .............................................126
SYMPTOM DIAGNOSIS ............................127
EXCESSIVE OPERATION FREQUENCY ...... ..127
Description .......................................................... ..127
Diagnosis Procedure .............................................127
UNEXPECTED BRAKE PEDAL REACTION ...128
Description .......................................................... ..128
Diagnosis Procedure .............................................128
THE BRAKING DISTANCE IS LONG ..............129
Description .......................................................... ..129
Diagnosis Procedure .............................................129
DOES NOT OPERATE .....................................130
Description .......................................................... ..130
Diagnosis Procedure .............................................130
BRAKE PEDAL VIBRATION OR OPERA-
TION SOUND OCCURS ...................................
131
Description .......................................................... ..131
Diagnosis Procedure .............................................131
VEHICLE JERKS DURING ..............................132
Description .......................................................... ..132
Diagnosis Procedure .............................................132
NORMAL OPERATING CONDITION ...............133
Description .......................................................... ..133
REMOVAL AND INSTALLATION .............134
WHEEL SENSOR ........................................... ..134
FRONT WHEEL SENSOR ..................................... ..134
FRONT WHEEL SENSOR : Exploded View .........134
FRONT WHEEL SENSOR : Removal and Instal-
lation ......................................................................
134
REAR WHEEL SENSOR ....................................... ..135
REAR WHEEL SENSOR : Exploded View ...........135
REAR WHEEL SENSOR : Removal and Installa-
tion ....................................................................... ..
135
SENSOR ROTOR ............................................136
FRONT SENSOR ROTOR ..................................... ..136
FRONT SENSOR ROTOR : Removal and Instal-
lation ......................................................................
136
REAR SENSOR ROTOR ....................................... ..136
REAR SENSOR ROTOR : Removal and Installa-
tion .........................................................................
136
ABS ACTUATOR AND ELECTRIC UNIT
(CONTROL UNIT) ...........................................
137
Removal and Installation .......................................137
YAW RATE/SIDE/DECEL G SENSOR ...........138
Exploded View .......................................................138
Removal and Installation .......................................138
STEERING ANGLE SENSOR .........................139
Removal and Installation .......................................139
VDC OFF SWITCH ..........................................140
Removal and Installation .......................................140
BRAKE ASSIST (WITH PREVIEW FUNC-
TION)
PRECAUTION ............... .............................
141
PRECAUTIONS ...............................................141
Precautions for Preview Function Service ........... ..141
SYSTEM DESCRIPTION ...........................142
COMPONENT PARTS ....................................142
Component Parts Location .................................. ..142
Component Description .........................................143
SYSTEM ..........................................................145
BRAKE ASSIST (WITH PREVIEW FUNCTION) ... ..145
BRAKE ASSIST (WITH PREVIEW FUNCTION) :
System Description ................................................
145
DTC/CIRCUIT DIAGNOSIS .......................146
BRAKE ASSIST (WITH PREVIEW FUNC-
TION) ...............................................................
146
Diagnosis Procedure ........................................... ..146
SYMPTOM DIAGNOSIS ............................147
NORMAL OPERATING CONDITION .............147
Description ........................................................... ..147
INTELLIGENT BRAKE ASSIST
PRECAUTION ............... .............................
148
PRECAUTIONS ...............................................148
Precautions for IBA System Service .................... ..148
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

PRECAUTIONSBRC-7
< PRECAUTION > [WITH VDC]
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and tires installed on the vehicle are the specified si ze and parts. Brake performance and controllability may
be negatively affected when other parts than the specified are installed.
 Brake stopping distance may become longer and steering stability may be negatively affected, when tires in
different size and combination or other parts than the specified are used.
 When a radio (including wiring), antenna and antenna lead line are located near ABS actuator and electric
unit (control unit), a malfunction or improper operation ma y occur for the control of VDC function, TCS func-
tion, ABS function, EBD function, hill start assist func tion or brake limited slip differential (BLSD) function.
 When the following items are replaced by other parts than genuine parts or modified, ABS warning lamp, brake warning lamp and VDC warning lamp may turn ON, and the control may not operate normally for VDC
function, TCS function, ABS function, EB D function, hill start assist function or brake limited slip differential
(BLSD) function.
- Suspension component parts (shock absorber, spring, bushing and others)
- Tire and wheel (other than the specified size)
- Brake component parts (brake pad, disc rotor, brake caliper and others)
- Engine component parts (ECM, muffler and others)
- Body reinforcement component parts (rollover bar, tower bar and others)
 When suspension, tire and brake component parts are excessively worn or deteriorated and the vehicle is
driven, ABS warning lamp, brake warning lamp and VDC warning lamp may tu\
rn ON, and the control may
not operate normally for VDC function, TCS function, ABS function, EBD function, hill start assist function or
brake limited slip differential (BLSD) function.
 ABS warning lamp, brake warning lamp and VDC warning lamp may turn ON, when only front wheel or rear wheel is rotated using a free roller. This is not a ma lfunction, because it is caused by wheel speed difference
between wheel that is rotated and wheel that is not rota ted. In this case, perform self-diagnosis, check self-
diagnosis results, and erase memory.
 When power supply voltage is not normal, ABS warning lamp, brake warning lamp and VDC warning lamp
turn ON. ABS actuator and electric unit (control unit) st ops control for VDC function, TCS function, ABS func-
tion, EBD function, hill start assist function or brake limited slip differential (BLSD) function. Ordinary brake
operates. After power supply returns to normal, ABS warning lamp, brake warning lamp and VDC warning
lamp turn OFF. The control becomes operative for VD C function, TCS function, ABS function, EBD function,
hill start assist function or brake li mited slip differential (BLSD) function.
 VDC warning lamp may turn ON and VDC function or TCS function may not normally operate, when driving
on a special road the is extremely slanted (bank in a circ uit course). This is not a malfunction if the status
returns to normal for VDC function or TCS function after the engine is started again. In this case, perform
self-diagnosis, check self-diagnosis results, and erase memory.
 A malfunction in yaw rate/side/decel G sensor syste m may be detected when the vehicle sharply turns dur-
ing a spin turn, acceleration turn or drift driving while VDC function or TCS function are OFF (VDC OFF
switch is pressed and VDC OFF indicator lamp is in ON st atus). This is not a malfunction if the status returns
to normal for VDC function or TCS function after the engine is started again. In this case, perform self-diag-
nosis, check self-diagnosis results, and erase memory
Precaution for Harness RepairINFOID:0000000006222558
 Solder the repair part, and wrap it with tape. [Twisted wire fray must be 110 mm (4.33 in) or less.]
SKIB8766E
Revision: 2010 May2011 QX56

COMPONENT PARTSBRC-11
< SYSTEM DESCRIPTION > [WITH VDC]
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4WD
1. ECM Refer to EC-16, "
Component Parts
Location". 2. Control valve & TCM
Refer to TM-10, "
A/T CONTROL
SYSTEM : Compon ent Parts Loca-
tion". 3. Front wheel sensor
4. ABS actuator and electric unit (con- trol unit) 5. Stop lamp switch 6. Steering angle sensor
7. VDC OFF switch 8. Yaw rate/side/decel G sensor 9. Rear wheel sensor
A. Front wheel hub and bearing assem- bly B. Inside engine room C. Brake pedal
D. ABS warning lamp, brake warning lamp, VDC warning lamp, VDC OFF
indicator lamp E. Back of spiral cable assembly F. Center console assembly
G. Under center console assembly H. Rear wheel hub and bearing assem- bly
Revision: 2010 May2011 QX56

BRC-12
< SYSTEM DESCRIPTION >[WITH VDC]
COMPONENT PARTS
1. Transfer control unit
Refer to DLN-10, "
Component Parts
Location". 2. ECM
Refer to EC-16, "
Component Parts
Location". 3. Control valve & TCM
Refer to TM-10, "
A/T CONTROL
SYSTEM : Component Parts Loca-
tion".
4. Front wheel sensor 5. ABS actuat or and electric unit (con-
trol unit) 6. Stop lamp switch
7. Steering angle sensor 8. VDC OFF switch 9. Yaw rate/side/decel G sensor
10. Rear wheel sensor
A. Front wheel hub and bearing assem- bly B. Inside engine room C. Brake pedal
JPFIC0186ZZ
Revision: 2010 May2011 QX56

COMPONENT PARTSBRC-13
< SYSTEM DESCRIPTION > [WITH VDC]
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BRC
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Component DescriptionINFOID:0000000006222560
*1: Models with Advanced Driver Assistance System
*2: Models with 4WD system
D. ABS warning lamp, brake warning lamp, VDC warning lamp, VDC OFF
indicator lamp E. Back of spiral cable assembly F. Center console assembly
G. Under center console assembly H. Rear wheel hub and bearing assem- bly
Component Reference/Function
ABS actuator and electric unit
(control unit) Motor/accumulator assembly
BRC-14, "
ABS Actuator and Electric Unit (Control Unit)"
Motor relay
Actuator relay (main relay)
ABS IN valve
ABS OUT valve
Cut valve 1
Cut valve 2
Suction valve 1
Suction valve 2
Control pressure sensor
*1
Accumulator pressure sensor
Master cylinder pressure sensor
Wheel sensor BRC-14, "
Wheel Sensor and Sensor Rotor"
Stop lamp switchBRC-15, "Stop Lamp Switch"
Steering angle sensorBRC-15, "Steering Angle Sensor"
Yaw rate/side/decel G sensorBRC-15, "Yaw Rate/Side/Decel G sensor"
Brake fluid level switch BRC-15, "Brake Fluid Level Switch"
Parking brake switchBRC-15, "Parking Brake Switch"
VDC OFF switchBRC-15, "VDC OFF Switch"
ECMMainly transmits the
following signals to ABS actuator and elec-
tric 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 elec-
tric 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 elec-
tric unit (control unit) via CAN communication.
 Current 4WD mode signal
ABS warning lamp
BRC-16, "
System Description"Brake warning lamp
VDC warning lamp
VDC OFF indicator lamp
Revision: 2010 May2011 QX56