2007 INFINITI QX56 brake

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

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-22
< SERVICE INFORMATION >[VDC/TCS/ABS]
TROUBLE DIAGNOSIS
Basic Inspection
INFOID:0000000003532780
BRAKE FLUID LEVEL, FLUID LEAK, AND BRAKE PAD INSPECTION
1. Check fluid level in the brake fluid reservoir. If fluid level is low, add fluid.
2. Check the brake piping and around the ABS actuator and electric unit (control unit) for leaks. If there is
leaking or seeping fluid, check the following items.
• If ABS actuator and electric unit (control unit) connection is loose, tighten the piping to the specified
torque and recheck for leaks.
WFWA0320E

TROUBLE DIAGNOSIS
BRC-23
< SERVICE INFORMATION >[VDC/TCS/ABS]
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• If there is damage to the connection flare nut or ABS actuator and electric unit (control unit) threads,
replace the damaged part and recheck for leaks.
• When there is fluid leaking or seeping from a fluid connection, use a clean cloth to wipe off the fluid and
recheck for leaks. If fluid is still seeping out, replace the damaged part. If the fluid is leaking at the ABS
actuator and electric unit (control unit), replace the ABS actuator and electric unit (control unit) assem-
bly.
CAUTION:
The ABS actuator and electric unit (control unit) cannot be disassembled and must be replaced
as an assembly.
3. Check the brake pads for excessive wear.
POWER SYSTEM TERMINAL LOOSENESS AND BATTERY INSPECTION
Make sure the battery positive cable, negative cable and ground connection are not loose. In addition, make
sure the battery is sufficiently charged.
ABS WARNING LAMP, SLIP INDICATOR LAMP AND VDC OFF INDICATOR LAMP INSPECTION
1. Make sure ABS warning lamp, SLIP indicator lamp and VDC OFF indicator lamp (when VDC OFF switch
is off), turn on for approximately 2 seconds when the ignition switch is turned ON. If they do not, check the
VDC OFF indicator lamp and the VDC OFF switch. Refer to BRC-53, "
Component Inspection". Check
CAN communications. If there are no errors with the VDC OFF switch or CAN communication system,
replace combination meter. Refer to DI-5
.
2. Make sure the lamps turn off approximately 2 seconds after the ignition switch is turned ON. If the lamp
does not turn off, conduct self-diagnosis of ABS actuator and electric unit (control unit). If no malfunctions
are detected in self-diagnosis, replace combination meter. Refer to DI-5
.
3. With the engine running, make sure the VDC OFF indicator lamp turns on and off when the VDC OFF
switch is turned on and off. If the indicator lamp status does not correspond to switch operation, check the
VDC OFF switch. Refer to BRC-53, "
Component Inspection".
4. After conducting the self-diagnosis, be sure to erase the error memory. Refer to BRC-26, "
CONSULT-II
Function (ABS)".
Warning Lamp and Indicator TimingINFOID:0000000003532781
×: ON
—: OFF
Control Unit Input/Output Signal StandardINFOID:0000000003532782
REFERENCE VALUE FROM CONSULT-II
CAUTION:
The display shows the control unit calculation data, so a normal value might be displayed even in the
event the output circuit (harness) is open or short circuited.
ConditionABS
warning lampVDC OFF
indicator lampSLIP
indicator lampRemarks
When the ignition switch is OFF — — — —
After the ignition switch is turned ON
for approx. 1 second×××—
After the ignition switch is turned ON
for approx. 2 seconds——— —
When the VDC OFF switch is
pressed (VDC function OFF)—×——
ABS/TCS/VDC malfunction×××—
××—When the ABS actuator and elec-
tric unit (control unit) is malfunc-
tioning (power supply or ground
malfunction).
When the VDC is malfunctioning —××—

BRC-24
< SERVICE INFORMATION >[VDC/TCS/ABS]
TROUBLE DIAGNOSIS
Monitor item Display contentData monitor
Note: Error inspection
checklist
ConditionReference value in
normal operation
N POSI SIGPNP switch signal ON/
OFF conditionA/T shift position = N position ON
LAN-7
A/T shift position = other than N
positionsOFF
P POSI SIGPNP switch signal ON/
OFF conditionA/T shift position P position ON
LAN-7
A/T shift position = other than P
positionsOFF
GEAR A/T gear position1st gear 1
— 2nd gear 2
3rd gear 3
4th gear 4
5th gear 5
FR RH SENSOR
FR LH SENSOR
RR RH SENSOR
RR LH SENSORWheel speedVehicle stopped 0 [km/h (MPH)]
BRC-34, "
Wheel Sensor
System Inspection"Vehicle running (Note 1)Almost in accor-
dance with speed-
ometer display
(within ±10%)
ACCEL POS SIG Open/close condition
of throttle valve (linked
with accelerator pedal).Accelerator pedal not de-
pressed (ignition switch is ON)0%
LAN-7
Depress accelerator pedal (ig-
nition switch is ON)0 to 100%
ENGINE SPEED With engine runningWith engine stopped 0 rpm
BRC-35, "
Engine System
Inspection"Engine runningAlmost in accor-
dance with ta-
chometer display
STR ANGLE SIGSteering angle detect-
ed by steering angle
sensorStraight-ahead Approx. 0 deg
BRC-36, "
Steering Angle
Sensor System"Steering wheel turned –756 to 756 deg
YAW RATE SENYaw rate detected by
yaw rate sensorVehicle stopped Approx. 0 d/sBRC-37, "
Yaw Rate/Side/
Decel G Sensor System
Inspection"Vehicle running –100 to 100 d/s
SIDE G-SENSORTransverse G detected
by side G-sensorVehicle stopped
Approx. 0 m/s
2BRC-37, "Yaw Rate/Side/
Decel G Sensor System
Inspection"Vehicle running
–16.7 to 16.7 m/s2
BATTERY VOLTBattery voltage sup-
plied to ABS actuator
and electric unit (con-
trol unit)Ignition switch ON 10 to 16VBRC-41, "
ABS/TCS/VDC
Control Unit Power and
Ground Systems Inspec-
tion"
STOP LAMP SWStop lamp switch oper-
ationBrake pedal depressed ONBRC-40, "
Stop Lamp
Switch System Inspec-
tion"Brake pedal not depressed OFF
OFF SWVDC OFF switch
ON/OFF status VDC OFF switch ON
(When VDC OFF indicator
lamp is ON)ON
BRC-53, "
Component In-
spection"VDC OFF switch OFF
(When VDC OFF indicator
lamp is OFF)OFF
ABS WARN LAMPABS warning lamp ON
condition (Note 2)ABS warning lamp ON ON
—
ABS warning lamp OFF OFF

TROUBLE DIAGNOSIS
BRC-25
< SERVICE INFORMATION >[VDC/TCS/ABS]
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MOTOR RELAYOperation status of mo-
tor and motor relayIgnition switch ON or running
(ABS not activated)OFF
BRC-39, "
Actuator Motor,
Motor Relay, and Circuit
Inspection"Ignition switch ON or engine
running (ABS activated)ON
ACTUATOR RLYActuator relay opera-
tion statusVehicle stopped (Ignition
switch ON)OFF
BRC-39, "
Actuator Motor,
Motor Relay, and Circuit
Inspection"Vehicle stopped (Engine run-
ning)ON
OFF LAMPVDC OFF indicator
lamp status (Note 3) When VDC OFF indicator
lamp is ONON
LAN-7
When VDC OFF indicator
lamp is OFFOFF
SLIP LAMPSLIP indicator lamp
status (Note 4)When SLIP indicator lamp is
ONON
LAN-7
When SLIP indicator lamp is
OFFOFF
FR LH IN SOL
FR LH OUT SOL
FR RH IN SOL
FR RH OUT SOL
RR RH IN SOL
RR RH OUT SOL
RR LH IN SOL
RR LH OUT SOLSolenoid valve opera-
tionActuator (solenoid) is active
(“ACTIVE TEST” with CON-
SULT-II) or actuator relay is in-
active (in fail-safe mode).ON
BRC-38, "
Solenoid and
VDC Change-Over Valve
System Inspection"
When actuator (solenoid) is not
active and actuator relay is ac-
tive (ignition switch ON).OFF
CV1
CV2
SV1
SV2VDC switch-over valve
statusWhen actuator (switch-over
valve) is active (“ACTIVE
TEST” with CONSULT-II) or
actuator relay is inactive (when
in fail-safe mode).ON
When actuator (switch-over
valve) is not active and actua-
tor relay is active (ignition
switch ON).OFF
DECEL G-SENLongitudinal accelera-
tion detected by Decel
G-SensorVehicle stopped Approx. 0 GBRC-37, "
Yaw Rate/Side/
Decel G Sensor System
Inspection"Vehicle running -1.7 to 1.7 G
PRESS SENSORBrake fluid pressure
detected by pressure
sensorDo not step on the Brake pedal
(When ignition switch is ON)Approx. 0 bar
—
Step on the Brake pedal (When
ignition switch is ON)-40 to 300 bar
FLUID LEV SWON/OFF status of
brake fluid level switchWhen brake fluid level switch
ONON
DI-26
When brake fluid level switch
OFF OFF
VDC SIGNAL
TCS SIGNAL
ABS SIGNAL
EBD SIGNALSignal statusVDC active
TCS active
ABS active
EBD activeON
VDC system
TCS system
ABS system
EBD system VDC not active
TCS not active
ABS not active
EBD not activeOFF Monitor item Display contentData monitor
Note: Error inspection
checklist
ConditionReference value in
normal operation

TROUBLE DIAGNOSIS
BRC-29
< SERVICE INFORMATION >[VDC/TCS/ABS]
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Note 1: If wheel sensor 2 for each wheel is indicated, check ABS actuator and electric unit (control unit) power supply voltage in addition
to wheel sensor circuit check.
Note 2: If multiple malfunctions are detected including CAN communication line [U1000], perform diagnosis for CAN communication line
first.
DATA MONITOR
Display Item List
CONTROLLER FAILURE
[ C 111 0 ]Internal malfunction of ABS actuator and electric unit (control
unit).BRC-35, "ABS/TCS/VDC
Control Unit Inspection"
CAN COMM CIRCUIT
[U1000]• CAN communication line is open or shorted.
• ABS actuator and electric unit (control unit) internal malfunction
• Battery voltage for ECM is suddenly interrupted for approxi-
mately 0.5 second or more.LAN-7 (Note 2)
SIDE G-SEN CIRCUIT
[C1146]Lateral G-sensor is malfunctioning, or signal line of lateral G-sen-
sor is open or shorted.BRC-37, "
Yaw Rate/
Side/Decel G Sensor
System Inspection"
BR FLUID LEVEL LOW
[C1155]Brake fluid level drops or circuit between ABS actuator and elec-
tric unit (control unit) and brake fluid level switch is open or
shorted.BRC-42, "Brake Fluid
Level Switch System In-
spection"
ENGINE SIGNAL 1
[C1130]Based on the signal from ECM, ABS actuator and electric unit
(control unit) judges that engine fuel cut system is malfunctioning.
BRC-35, "
Engine System
Inspection"
ENGINE SIGNAL 2
[C1131]Based on the signal from ECM, ABS actuator and electric unit
(control unit) judges that engine fuel cut system is malfunctioning.
ENGINE SIGNAL 3
[C1132]Based on the signal from ECM, ABS actuator and electric unit
(control unit) judges that engine fuel cut system is malfunctioning.
ENGINE SIGNAL 4
[C1133]Based on the signal from ECM, ABS actuator and electric unit
(control unit) judges that engine fuel cut system is malfunctioning.
ENGINE SIGNAL 6
[C1136]Based on the signal from ECM, ABS actuator and electric unit
(control unit) judges that engine fuel cut system is malfunctioning.
ACTUATOR RLY
[C1140]ABS actuator relay or circuit malfunction.BRC-39, "
Actuator Mo-
tor, Motor Relay, and Cir-
cuit Inspection"
PRESS SEN CIRCUIT
[C1142]ABS pressure sensor circuit malfunction.BRC-45, "Pressure Sen-
sor System Inspection"
VARIANT CODING
[C1170]V coding is not malfunctioning.BRC-35, "ABS/TCS/VDC
Control Unit Inspection"
ABS ACTIVE BOOSTER SV NG
[C1178]Active booster solenoid is malfunctioning, or signal line of active
booster servo is open or shorted.BRC-43, "Active Booster
System Inspection"
ABS DELTA S SEN NG
[C1179]Delta stroke sensor malfunctioning, or signal line of delta stroke
sensor is open or shorted.BRC-44, "Delta Stroke
Sensor System Inspec-
tion"
ABS ACTIVE BOOSTER RE-
SPONSE NG
[C1181]Active booster response is malfunctioning, or signal line of active
booster response is open or shorted.BRC-43, "Active Booster
System Inspection"
ABS BRAKE RELEASE SW NG
[C1184]Brake release switch is malfunctioning, or signal line of brake re-
lease switch is open or shorted.BRC-43, "Active Booster
System Inspection"
ABS ACC CU INTERNAL NG
[C1185]ICC control unit internal malfunction.BRC-48, "ICC System In-
spection"
ABS BRAKE BOOSTER DEFECT
[C1189]Brake booster is defective or malfunctioning.BRC-43, "Active Booster
System Inspection"
Self-diagnostic item Malfunction detecting condition Check system