2007 INFINITI QX56 ABS

BRC-6
< SERVICE INFORMATION >[VDC/TCS/ABS]
PREPARATION
PREPARATION
Special Service ToolINFOID:0000000003532766
The actual shapes of Kent-Moore tools may differ from those of special service tools illustrated here.
Commercial Service ToolINFOID:0000000003532767
Tool number
(Kent-Moore No.)
Tool nameDescription
—
(J-45741)
ABS active wheel sensor testerChecking operation of ABS active wheel sen-
sors
WFIA0101E
Tool nameDescription
1. Flare nut crowfoot
2. Torque wrenchRemoving and installing brake piping
a: 10mm (0.39 in)/12mm (0.47 in)
S-NT360

SYSTEM DESCRIPTION
BRC-7
< SERVICE INFORMATION >[VDC/TCS/ABS]
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SYSTEM DESCRIPTION
System ComponentINFOID:0000000003532768
WFIA0222E

BRC-8
< SERVICE INFORMATION >[VDC/TCS/ABS]
SYSTEM DESCRIPTION
ABS Function
INFOID:0000000003532769
• The Anti-Lock Brake System detects wheel revolution while braking and improves handling stability during
sudden braking by electrically preventing wheel lockup. Maneuverability is also improved for avoiding obsta-
cles.
• If the electrical system malfunctions, the Fail-Safe function is activated, the ABS becomes inoperative and
the ABS warning lamp turns on.
• The electrical system can be diagnosed using CONSULT-II.
• During ABS operation, the brake pedal may vibrate lightly and a mechanical noise may be heard. This is
normal.
• Just after starting the 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.
EBD FunctionINFOID:0000000003532770
• Electronic Brake Distribution is a function that detects subtle slippages between the front and rear wheels
during braking, and it improves handling stability by electronically controlling the brake fluid pressure which
results in reduced rear wheel slippage.
• If the electrical system malfunctions, the Fail-Safe function is activated, the EBD and ABS become inopera-
tive, and the ABS warning lamp and BRAKE warning lamp are turned on.
• The electrical system can be diagnosed using CONSULT-II.
• During EBD operation, the brake pedal may vibrate lightly and a mechanical noise may be heard. This is
normal.
• Just after starting the 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.
TCS FunctionINFOID:0000000003532771
• Spinning of the drive wheels is detected by the ABS actuator and electric unit (control unit) using inputs from
the wheel speed sensors. If wheel spin occurs, the drive wheel right and left brake fluid pressure control and
engine fuel cut are activated while the throttle value is restricted to reduce the engine torque and decrease
the amount of wheel spin. In addition, the throttle opening is controlled to achieve the optimum engine
torque.
• Depending on road condition, the vehicle may have a sluggish feel. This is normal, because optimum trac-
tion has the highest priority during TCS operation.
• TCS may be activated during sudden vehicle acceleration, wide open throttle acceleration, sudden transmis-
sion shifts or when the vehicle is driven on a road with a varying surface friction coefficient.
• The SLIP indicator lamp flashes to inform the driver of TCS operation.
VDC FunctionINFOID:0000000003532772
• In addition to the ABS/TCS function, the driver steering amount and brake operation amount are detected
from the steering angle sensor and front and rear pressure sensors, and the vehicle's driving status (amount
of under steering/over steering) is determined using inputs from the yaw rate sensor/side G sensor, wheel
speed sensors, etc. and this information is used to improve vehicle stability by controlling the braking and
engine torque application to the wheels.
• The SLIP indicator lamp flashes to inform the driver of VDC operation.
• During VDC operation, the vehicle body and brake pedal may vibrate lightly and a mechanical noise may be
heard. This is normal.
• The ABS warning lamp, VDC OFF indicator lamp and SLIP indicator lamp may turn on when the vehicle is
subject to strong shaking or large vibration, such as when the vehicle is on a turn table or a ship while the
engine is running or on a steep slope. In this case, restart the engine on a normal road and if the ABS warn-
ing lamp, VDC OFF indicator lamp and SLIP indicator lamp turn off, there is no problem.
Fail-Safe FunctionINFOID:0000000003532773
CAUTION:
If the Fail-Safe function is activated, perform the Self Diagnosis for ABS/TCS/VDC system.
ABS/EBD SYSTEM

SYSTEM DESCRIPTION
BRC-9
< SERVICE INFORMATION >[VDC/TCS/ABS]
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In case of an electrical malfunction with the ABS, the ABS warning lamp, VDC OFF indicator lamp and SLIP
indicator lamp will turn on. In case of an electrical malfunction with the EBD system, the BRAKE warning lamp,
ABS warning lamp, VDC OFF indicator lamp and SLIP indicator lamp will turn on.
The system will revert to one of the following conditions of the Fail-Safe function.
1. For ABS malfunction, only the EBD is operative and the condition of the vehicle is the same condition of
vehicles without ABS/TCS/VDC system.
2. For EBD malfunction, the EBD and ABS become inoperative, and the condition of the vehicle is the same
as the condition of vehicles without ABS/TCS/VDC or EBD system.
VDC/TCS SYSTEM
In case of TCS/VDC system malfunction, the VDC OFF indicator lamp and SLIP indicator lamp are turned on
and the condition of the vehicle is the same as the condition of vehicles without TCS/VDC system. In case of
an electrical malfunction with the TCS/VDC system, the ABS control continues to operate normally without
TCS/VDC control.
ACTIVE BOOSTER
The active brake booster consists of a vacuum booster, an active booster control group and a delta stroke
sensor. In case of brake booster system malfunction due to loss of vacuum, the delta stroke sensor will signal
the ABS actuator and electric unit (control unit) that a booster failure has occurred. The active booster then
applies supplemental force to the master cylinder relative to the amount of force exerted on the brake pedal.
Hydraulic Circuit DiagramINFOID:0000000003532774
WFIA0187E

BRC-10
< SERVICE INFORMATION >[VDC/TCS/ABS]
CAN COMMUNICATION
CAN COMMUNICATION
System DescriptionINFOID:0000000003532775
Refer to LAN-4.

TROUBLE DIAGNOSIS
BRC-11
< SERVICE INFORMATION >[VDC/TCS/ABS]
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TROUBLE DIAGNOSIS
How to Perform Trouble Diagnosis for Quick and Accurate RepairINFOID:0000000003532776
INTRODUCTION
The ABS/TCS/VDC system has an electronic control unit to control
major functions. The control unit accepts input signals from sensors
and controls actuator operation. It is also important to check for con-
ventional malfunctions such as air leaks in the booster or lines, lack
of brake fluid, or other malfunctions with the brake system.
It is much more difficult to diagnose a malfunction that occurs inter-
mittently rather than continuously. Most intermittent malfunctions are
caused by poor electrical connections or wiring. In this case, careful
checking of suspicious circuits may help prevent the replacement of
good parts.
A visual check only may not find the cause of the malfunction, so a
road test should be performed.
Before undertaking actual checks, take just a few minutes to talk with
a customer who approaches with an ABS/TCS/VDC complaint. The
customer is a very good source of information, especially for inter-
mittent malfunctions. Through the talks with the customer, find out
what symptoms are present and under what conditions they occur.
Start your diagnosis by looking for “conventional” malfunctions first.
This is one of the best ways to troubleshoot brake malfunctions on
an ABS/TCS/VDC equipped vehicle. Also check related Service Bul-
letins for information.
SEF233G
SEF234G

BRC-12
< SERVICE INFORMATION >[VDC/TCS/ABS]
TROUBLE DIAGNOSIS
WORK FLOW
CLARIFY CONCERN
WFIA0534E

TROUBLE DIAGNOSIS
BRC-13
< SERVICE INFORMATION >[VDC/TCS/ABS]
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• A customer's description of a vehicle concern may vary depending
on the individual. It is important to clarify the customer's concern.
• Ask the customer about what symptoms are present under what
conditions. Use this information to reproduce the symptom while
driving.
• It is also important to use the diagnosis sheet to understand what
type of trouble the customer is having.
EXAMPLE OF DIAGNOSIS SHEET
SBR339B
WFIA0097E