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BRC-6
[VDC/TCS/ABS]
PREPARATION
Revision: November 20092006 QX56
PREPARATIONPFP:00002
Special Service ToolEFS005G1
The actual shapes of Kent-Moore tools may differ from those of special service tools illustrated here.
Commercial Service ToolsEFS005G2
Tool number
(Kent-Moore No.)
Tool nameDescription
—
(J-45741)
ABS active wheel sensor tester Checking operation of ABS active wheel sen-
sors
WFIA0101E
Tool name
Description
1. Flare nut crowfoot
2. Torque wrench Removing and installing brake piping
a: 10mm (0.39 in)/12mm (0.47 in)
S-NT360
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SYSTEM DESCRIPTIONBRC-7
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System ComponentsEFS004XB
WFIA0222E
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![INFINITI QX56 2006 Factory Service Manual BRC-8
[VDC/TCS/ABS]
SYSTEM DESCRIPTION
Revision: November 20092006 QX56
ABS FunctionEFS004XC
The Anti-Lock Brake System detects wheel revolution while braking and improves handling stability during
s INFINITI QX56 2006 Factory Service Manual BRC-8
[VDC/TCS/ABS]
SYSTEM DESCRIPTION
Revision: November 20092006 QX56
ABS FunctionEFS004XC
The Anti-Lock Brake System detects wheel revolution while braking and improves handling stability during
s](/manual-img/42/57028/w960_57028-1034.png)
BRC-8
[VDC/TCS/ABS]
SYSTEM DESCRIPTION
Revision: November 20092006 QX56
ABS FunctionEFS004XC
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
obstacles.
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 FunctionEFS004XD
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 inoper-
ative, 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 FunctionEFS004XE
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 opti-
mum 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 trans-
mission 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 FunctionEFS004XF
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 sen-
sor, 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
warning lamp, VDC OFF indicator lamp and SLIP indicator lamp turn off, there is no problem.
Fail-Safe FunctionEFS004XG
CAUTION:
If the Fail-Safe function is activated, perform the Self Diagnosis for ABS/TCS/VDC system.
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ABS/EBD SYSTEM
In case of an electrical malfunction with the ABS, the ABS warning lamp, VDC OFF indic INFINITI QX56 2006 Factory Service Manual SYSTEM DESCRIPTIONBRC-9
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ABS/EBD SYSTEM
In case of an electrical malfunction with the ABS, the ABS warning lamp, VDC OFF indic](/manual-img/42/57028/w960_57028-1035.png)
SYSTEM DESCRIPTIONBRC-9
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ABS/EBD SYSTEM
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 DiagramEFS004XH
WFIA0187E
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BRC-10
[VDC/TCS/ABS]
CAN COMMUNICATION
Revision: November 20092006 QX56
CAN COMMUNICATIONPFP:23710
System DescriptionEFS004XI
Refer to LAN-26, "CAN COMMUNICATION" .
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How to Perform Trouble Diagnoses for Quick and Accurate RepairEFS004XJ
INT INFINITI QX56 2006 Factory Service Manual TROUBLE DIAGNOSISBRC-11
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How to Perform Trouble Diagnoses for Quick and Accurate RepairEFS004XJ
INT](/manual-img/42/57028/w960_57028-1037.png)
TROUBLE DIAGNOSISBRC-11
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How to Perform Trouble Diagnoses for Quick and Accurate RepairEFS004XJ
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 problems such as air leaks in the booster or lines, lack of
brake fluid, or other problems with the brake system.
It is much more difficult to diagnose a problem that occurs intermit-
tently rather than continuously. Most intermittent problems are
caused by poor electrical connections or faulty wiring. In this case,
careful checking of suspicious circuits may help prevent the replace-
ment of good parts.
A visual check only may not find the cause of the problem, 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 on such problems,
especially intermittent ones. 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” problems first. This
is one of the best ways to troubleshoot brake problems on an ABS/
TCS/VDC equipped vehicle. Also check related Service Bulletins for
information.
SEF233G
SEF234G
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BRC-12
[VDC/TCS/ABS]
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
WORK FLOW
WFIA0358E
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TROUBLE DIAGNOSISBRC-13
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CLARIFY CONCERN
A customer's description of a vehicle concern may vary depend-
ing on the individual. It is important to clarify the customer's con-
cern.
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