2007 INFINITI QX56 ABS

BR-2
< SERVICE INFORMATION >
PRECAUTIONS
SERVICE INFORMATION
PRECAUTIONS
Precaution for Supplemental Restraint System (SRS) "AIR BAG" and "SEAT BELT
PRE-TENSIONER"
INFOID:0000000003532717
The Supplemental Restraint System such as “AIR BAG” and “SEAT BELT PRE-TENSIONER”, used along
with a front seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain
types of collision. This system includes seat belt switch inputs and dual stage front air bag modules. The SRS
system uses the seat belt switches to determine the front air bag deployment, and may only deploy one front
air bag, depending on the severity of a collision and whether the front occupants are belted or unbelted.
Information necessary to service the system safely is included in the SRS and SB section of this Service Man-
ual.
WARNING:
• To avoid rendering the SRS inoperative, which could increase the risk of personal injury or death in
the event of a collision which would result in air bag inflation, all maintenance must be performed by
an authorized NISSAN/INFINITI dealer.
• Improper maintenance, including incorrect removal and installation of the SRS, can lead to personal
injury caused by unintentional activation of the system. For removal of Spiral Cable and Air Bag
Module, see the SRS section.
• Do not use electrical test equipment on any circuit related to the SRS unless instructed to in this
Service Manual. SRS wiring harnesses can be identified by yellow and/or orange harnesses or har-
ness connectors.
Precaution for Brake SystemINFOID:0000000003532718
• Always use recommended brake fluid. Refer to MA-10 .
• Do not reuse drained brake fluid.
• Be careful not to splash brake fluid on painted areas.
• To clean or wash all parts of master cylinder, disc brake caliper and wheel cylinder, use clean brake fluid.
• Do not use mineral oils such as gasoline or kerosene. They will ruin rubber parts of the hydraulic system.
• Use flare nut wrench when removing and installing brake tube.
• Always check tightening torque when installing brake lines.
• Before working, turn ignition switch to OFF and disconnect con-
nectors for ABS actuator and electric unit (control unit) or battery
terminals.
• Burnish the brake contact surfaces after refinishing or replacing
drums or rotors, after replacing pads or linings, or if a soft pedal
occurs at very low mileage.
Refer to BR-20, "
Disassembly and Assembly of Brake Caliper" .
WARNING:
• Clean brake pads and shoes with a waste cloth, then wipe
with a dust collector.
SBR686C

BR-8
< SERVICE INFORMATION >
BRAKE FLUID
BRAKE FLUID
On Board InspectionINFOID:0000000003532724
LEVEL CHECK
• Make sure the fluid level in reservoir tank is within the standard
(between MAX and MIN lines).
• Visually check around reservoir tank for fluid leaks.
• If fluid level is excessively low, check brake system for leaks.
• If brake warning lamp remains illuminated after parking lever is
released, check brake system for fluid leakage.
Drain and RefillINFOID:0000000003532725
CAUTION:
• Refill with new brake fluid. Refer to MA-10
.
• Do not reuse drained brake fluid.
• Do not let brake fluid splash on the painted surfaces of the body. This might damage the paint, so
when splashing it, immediately wipe off the area and wash away with water.
• Before servicing, disconnect actuator connector or battery negative cable.
1. Connect a vinyl tube to each bleed valve.
2. Depress brake pedal, loosen each bleed valve, and gradually
remove brake fluid.
3. Make sure there is no foreign material in reservoir tank, and refill
with new brake fluid.
4. Rest foot on brake pedal. Loosen bleed valve. Slowly depress
pedal until it stops. Tighten bleed valve. Release brake pedal.
Repeat this process a few times, then pause to add new brake
fluid to master cylinder. Continue until new brake fluid flows out.
Bleed air from brake system. Refer to BR-8, "
Bleeding Brake
System" .
Bleeding Brake SystemINFOID:0000000003532726
CAUTION:
While bleeding, pay attention to master cylinder fluid level.
1. Turn ignition switch OFF and disconnect ABS actuator and electric unit (control unit) connector or battery
negative cable.
2. Connect a vinyl tube to the rear right bleed valve.
3. Fully depress brake pedal 4 to 5 times.
LFIA0225E
SBR419C
SBR995

BR-14
< SERVICE INFORMATION >
BRAKE MASTER CYLINDER
• Refill brake fluid and bleed air. Refer to BR-8, "Bleeding Brake System".
CAUTION:
• Refill with new brake fluid. Refer to MA-10
.
• Do not reuse drained brake fluid.
• Adjust brake pedal. Refer to BR-5, "
Inspection and Adjustment" .
Disassembly and AssemblyINFOID:0000000003532733
DISASSEMBLY
CAUTION:
• Master cylinder cannot be disassembled.
• Remove reservoir tank only when absolutely necessary.
Pull reservoir tank off master cylinder sub-assembly, then remove grommets from master cylinder sub-assem-
bly body.
ASSEMBLY
CAUTION:
• Never use mineral oil such as kerosene, gasoline during the cleaning and assembly process.
• Do not drop parts. If a part is dropped, do not use it.
1. Apply brake fluid or rubber grease to new grommets, then insert into master cylinder sub-assembly. Refer
to GI-45
.
CAUTION:
Do not reuse grommet.
2. Install reservoir tank onto master cylinder sub-assembly.

BR-16
< SERVICE INFORMATION >
BRAKE BOOSTER
• Be careful not to damage brake booster stud bolt threads. If brake booster is tilted or inclined during
installation, dash panel may damage the threads.
• Attach the check valve in the correct direction.
1. Remove engine room cover with power tool. Refer to EM-12, "
Removal and Installation" .
2. Remove engine air duct assembly. Refer to EM-15, "
Removal and Installation" .
3. Remove brake piping from brake master cylinder.
4. Remove brake master cylinder. Refer to BR-13, "
Removal and Installation" .
5. Remove vacuum hose from brake booster. Refer to BR-17
.
6. Disconnect active boost and delta stroke sensor harness connectors from brake booster assembly.
7. Remove brake pedal attachment snap pin and clevis pin from inside the vehicle.
8. Remove nuts on brake booster and brake pedal assembly.
9. Remove brake booster assembly from dash panel.
INSPECTION AFTER REMOVAL
Output Rod Length Inspection
1. Using a handy vacuum pump, apply a vacuum of – 66.7 kPa (–
500 mmHg, –19.69 inHg) to brake booster.
2. Check output rod length.
INSTALLATION
1. Loosen lock nut to adjust input rod length so that the length B (in
the figure) satisfies the specified value.
2. After adjusting “B”, temporarily tighten lock nut and install
booster assembly to the vehicle.
• Install a gaskets and spacer block between booster assembly
and the dash panel.
3. Connect brake pedal with clevis of input rod.
4. Install pedal bracket mounting nuts and tighten them to the
specified torque.
5. Install brake piping from brake master cylinder to ABS actuator. Refer to BR-10, "
Hydraulic Circuit".
6. Connect active boost and delta stroke sensor harness connectors to brake booster assembly.
7. Connect vacuum hose to brake booster.
8. Install master cylinder to booster assembly. Refer to BR-13, "
Removal and Installation" .
9. Adjust the height and play of brake pedal.
10. Tighten lock nut of input rod to specification.
11. Install engine air duct assembly. Refer to EM-15, "
Removal and Installation" .
12. Install engine room cover with power tool. Refer to EM-12, "
Removal and Installation" .
13. Refill with new brake fluid and bleed air. Refer to BR-8, "
Bleeding Brake System" .
SBR208E
Standard dimension : 15.6 − 15.9 mm (0.614 − 0.626 in)
[when vacuum is – 66.7 kPa (– 500 mmHg, – 19.69 inHg)]
Length “B” : 151 mm (5.94 in)
WFIA0382E

BRC-1
BRAKES
C
D
E
G
H
I
J
K
L
M
SECTION BRC
A
B
BRC
N
O
P
CONTENTS
BRAKE CONTROL SYSTEM
VDC/TCS/ABS
SERVICE INFORMATION ............................
3
PRECAUTIONS ...................................................3
Precaution for Supplemental Restraint System
(SRS) "AIR BAG" and "SEAT BELT PRE-TEN-
SIONER" ...................................................................
3
Precaution for Brake System ....................................3
Precaution When Using CONSULT-II .......................3
Precaution for Brake Control .....................................4
Precaution for CAN System ......................................4
PREPARATION ...................................................6
Special Service Tool .................................................6
Commercial Service Tool ..........................................6
SYSTEM DESCRIPTION .....................................7
System Component ...................................................7
ABS Function ............................................................8
EBD Function ............................................................8
TCS Function ............................................................8
VDC Function ............................................................8
Fail-Safe Function .....................................................8
Hydraulic Circuit Diagram .........................................9
CAN COMMUNICATION ....................................10
System Description .................................................10
TROUBLE DIAGNOSIS .....................................11
How to Perform Trouble Diagnosis for Quick and
Accurate Repair ......................................................
11
Component Parts and Harness Connector Loca-
tion ..........................................................................
14
Schematic ...............................................................15
Wiring Diagram - VDC - ..........................................16
Basic Inspection ......................................................22
Warning Lamp and Indicator Timing .......................23
Control Unit Input/Output Signal Standard ..............23
CONSULT-II Function (ABS) ..................................26
TROUBLE DIAGNOSIS FOR SELF-DIAG-
NOSTIC ITEMS .................................................
34
Wheel Sensor System Inspection ............................34
Engine System Inspection .......................................35
ABS/TCS/VDC Control Unit Inspection ...................35
Steering Angle Sensor System ................................36
Yaw Rate/Side/Decel G Sensor System Inspec-
tion ...........................................................................
37
Solenoid and VDC Change-Over Valve System
Inspection ................................................................
38
Actuator Motor, Motor Relay, and Circuit Inspec-
tion ...........................................................................
39
Stop Lamp Switch System Inspection .....................40
ABS/TCS/VDC Control Unit Power and Ground
Systems Inspection .................................................
41
Brake Fluid Level Switch System Inspection ...........42
Active Booster System Inspection ...........................43
Delta Stroke Sensor System Inspection ..................44
Pressure Sensor System Inspection .......................45
Steering Angle Sensor Safe Mode Inspection .........47
CAN Communication System Inspection .................48
ICC System Inspection ............................................48
Inspection for Self-Diagnosis Result "ST ANG
SEN SIGNAL" ..........................................................
48
Inspection for Self-Diagnosis Result "DECEL G
SEN SET" ................................................................
49
TROUBLE DIAGNOSES FOR SYMPTOMS .....50
ABS Works Frequently ............................................50
Unexpected Pedal Action ........................................50
Long Stopping Distance ..........................................51
ABS Does Not Work ................................................51
Pedal Vibration or ABS Operation Noise .................51
Vehicle Jerks During TCS/VDC Activation ..............52
Component Inspection .............................................53
ON-VEHICLE SERVICE ....................................54
Adjustment of Steering Angle Sensor Neutral Po-
sition ........................................................................
54
Calibration of Decel G Sensor .................................54

PRECAUTIONS
BRC-3
< SERVICE INFORMATION >[VDC/TCS/ABS]
C
D
E
G
H
I
J
K
L
MA
B
BRC
N
O
P
SERVICE INFORMATION
PRECAUTIONS
Precaution for Supplemental Restraint System (SRS) "AIR BAG" and "SEAT BELT
PRE-TENSIONER"
INFOID:0000000003532761
The Supplemental Restraint System such as “AIR BAG” and “SEAT BELT PRE-TENSIONER”, used along
with a front seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain
types of collision. This system includes seat belt switch inputs and dual stage front air bag modules. The SRS
system uses the seat belt switches to determine the front air bag deployment, and may only deploy one front
air bag, depending on the severity of a collision and whether the front occupants are belted or unbelted.
Information necessary to service the system safely is included in the SRS and SB section of this Service Man-
ual.
WARNING:
• To avoid rendering the SRS inoperative, which could increase the risk of personal injury or death in
the event of a collision which would result in air bag inflation, all maintenance must be performed by
an authorized NISSAN/INFINITI dealer.
• Improper maintenance, including incorrect removal and installation of the SRS, can lead to personal
injury caused by unintentional activation of the system. For removal of Spiral Cable and Air Bag
Module, see the SRS section.
• Do not use electrical test equipment on any circuit related to the SRS unless instructed to in this
Service Manual. SRS wiring harnesses can be identified by yellow and/or orange harnesses or har-
ness connectors.
Precaution for Brake SystemINFOID:0000000003532762
CAUTION:
• Refer to MA-10
for recommended brake fluid.
• Never reuse drained brake fluid.
• Be careful not to splash brake fluid on painted areas; it may cause paint damage. If brake fluid is
splashed on painted areas, wash it away with water immediately.
• To clean or wash all parts of master cylinder and disc brake caliper, use clean brake fluid.
• Never use mineral oils such as gasoline or kerosene. They will ruin rubber parts of the hydraulic sys-
tem.
• Use flare nut wrench when removing and installing brake
tube.
• If a brake fluid leak is found, the part must be disassembled
without fail. Then it has to be replaced with a new one if a
defect exists.
• Turn the ignition switch OFF and remove the connector of the
ABS actuator and electric unit (control unit) or the battery ter-
minal before performing the work.
• Always torque brake lines when installing.
• Burnish the brake contact surfaces after refinishing or replac-
ing rotors, after replacing pads, or if a soft pedal occurs at
very low mileage.
Refer to BR-20, "
Disassembly and Assembly of Brake Caliper" (front disc brake) or BR-26, "Brake
Caliper" (rear disc brake).
WARNING:
• Clean brake pads and shoes with a waste cloth, then wipe with a dust collector.
Precaution When Using CONSULT-IIINFOID:0000000003532763
When connecting CONSULT-II to data link connector, connect them through CONSULT-II CONVERTER.
CAUTION:
If CONSULT-II is used with no connection of CONSULT-II CONVERTER, malfunctions might be
detected in self-diagnosis depending on control unit which carries out CAN communication.
CHECK POINTS FOR USING CONSULT-II
1. Has CONSULT-II been used without connecting CONSULT-II CONVERTER on this vehicle?
SBR686C

BRC-4
< SERVICE INFORMATION >[VDC/TCS/ABS]
PRECAUTIONS
• If YES, GO TO 2.
• If NO, GO TO 5.
2. Is there any indication other than indications relating to CAN communication system in the self-diagnosis
results?
• If YES, GO TO 3.
• If NO, GO TO 4.
3. Based on self-diagnosis results unrelated to CAN communication, carry out the inspection.
4. Malfunctions may be detected in self-diagnosis depending on control units carrying out CAN communica-
tion. Therefor, erase the self-diagnosis results.
5. Diagnose CAN communication system. Refer to LAN-7
.
Precaution for Brake ControlINFOID:0000000003532764
• During ABS operation, the brake pedal may vibrate lightly and a mechanical noise may be heard. This is
normal.
• Just after starting vehicle, the brake pedal may vibrate or a motor operating noise may be heard from engine
compartment. This is a normal status of operation check.
• Stopping distance may be longer than that of vehicles without ABS when vehicle drives on rough, gravel, or
snow-covered (fresh, deep snow) roads.
• When an error is indicated by ABS or another warning lamp, collect all necessary information from customer
(what symptoms are present under what conditions) and check for simple causes before starting diagnosis.
Besides electrical system inspection, check booster operation, brake fluid level, and fluid leaks.
• If incorrect tire sizes or types are installed on the vehicle or brake pads are not Genuine NISSAN parts, stop-
ping distance or steering stability may deteriorate.
• If there is a radio, antenna or related wiring near control module, ABS function may have a malfunction or
error.
• If aftermarket parts (car stereo, CD player, etc.) have been installed, check for incidents such as harness
pinches, open circuits or improper wiring.
• If the following components are replaced with non-genuine components or modified, the VDC OFF indicator
lamp and SLIP indicator lamp may turn on or the VDC system may not operate properly. Components
related to suspension (shock absorbers, struts, springs, bushings, etc.), tires, wheels (exclude specified
size), components related to brake system (pads, rotors, calipers, etc.), components related to engine (muf-
fler, ECM, etc.), components related to body reinforcement (roll bar, tower bar, etc.).
• Driving with broken or excessively worn suspension components, tires or brake system components may
cause the VDC OFF indicator lamp and the SLIP indicator lamp to turn on, and the VDC system may not
operate properly.
• When the TCS or VDC is activated by sudden acceleration or sudden turn, some noise may occur. The
noise is a result of the normal operation of the TCS and VDC.
• When driving on roads which have extreme slopes (such as mountainous roads) or high banks (such as
sharp curves on a freeway), the VDC may not operate normally, or the VDC warning lamp and the SLIP indi-
cator lamp may turn on. This is not a problem if normal operation can be resumed after restarting the engine.
• Sudden turns (such as spin turns, acceleration turns), drifting, etc. with VDC turned off may cause the yaw
rate/side/decel G sensor to indicate a problem. This is not a problem if normal operation can be resumed
after restarting the engine.
Precaution for CAN SystemINFOID:0000000003532765
• Do not apply voltage of 7.0V or higher to terminal to be measured.
• Maximum open terminal voltage of tester in use must be less than 7.0V.
• Before checking harnesses, turn ignition switch OFF and disconnect battery negative cable.

PRECAUTIONS
BRC-5
< SERVICE INFORMATION >[VDC/TCS/ABS]
C
D
E
G
H
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J
K
L
MA
B
BRC
N
O
P
• Area to be repaired must be soldered and wrapped with tape.
Make sure that fraying of twisted wire is within 110 mm (4.33 in).
• Do not make a bypass connection to repaired area. (If the circuit is
bypassed, characteristics of twisted wire will be lost.)
PKIA0306E
PKIA0307E