brake fluid INFINITI QX56 2011 Factory Workshop Manual

SYSTEMBRC-25
< SYSTEM DESCRIPTION > [WITH VDC]
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VDC Warning Lamp
 Turns ON when either VDC function,
TCS function, ABS function or EBD function, hill start assist function or
brake limited slip differential (BLSD) function is malfunctioning.
 Turns ON when ignition switch turns ON and turns OFF when the system is normal, for bulb check purposes.
CONDITION FOR TURN ON THE INDICATOR LAMP
VDC OFF Indicator Lamp
 Turns ON when VDC function and TCS function are s witched to non-operational status (OFF) by VDC OFF
switch.
 Turns ON when ignition switch turns ON and turns OFF when the system is normal, for bulb check purposes.
*: Models with 4WD system
Fail-safeINFOID:0000000006228184
VDC FUNCTION, TCS FUNCTION, hill start assi st FUNCTION AND BRAKE LIMITED SLIP DIFFER-
ENTIAL (BLSD) FUNCTION
VDC warning lamp in combination meter turn ON w hen a malfunction occurs in system [ABS actuator and
electric unit (control unit)]. The control is suspended for VDC function, TCS function, hill start assist function
and brake limited slip differential (BLSD) function. T he Vehicle status becomes the same as models without
VDC function, TCS function, hill star t assist function and brake limited slip differential (BLSD) function. How-
ever, ABS function and EBD f unction are operated normally.
When brake fluid is less than the specified level (brake fluid level
switch ON) ON
ABS function is malfunctioning OFF
EBD function is malfunctioning ON
Accumulator is low pressure ON
Motor system is malfunctioning ON
Ignition power supply system is malfunctioning ON Condition (status) Brake warning lamp
Condition (status) VDC warning lamp
Ignition switch OFF OFF
For approx. 1 seconds after the ignition switch is turned ON ON
Approx. 1 seconds after ignition switch is turned ON (when the
system is in normal operation) OFF
VDC function is malfunctioning ON
TCS function is malfunctioning ON
ABS function is malfunctioning ON
EBD function is malfunctioning ON
hill start assist function is malfunctioning ON
Brake limited slip differential (BLSD) function is malfunctioning ON
VDC function is operating Blinking
TCS function is operating Blinking
Condition (status) VDC OFF indicator lamp
Ignition switch OFF OFF
For approx. 1 seconds after the ignition switch is turned ON ON
Approx. 1 seconds after ignition switch is turned ON (when the
system is in normal operation) OFF
When VDC OFF switch is ON (VDC function and TCS function are
OFF) ON
4WD mode: 4L
*ON
Revision: 2010 May2011 QX56

SYSTEMBRC-27
< SYSTEM DESCRIPTION > [WITH VDC]
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C1120 When a malfunction is detec ted in front LH ABS IN valve.
The following functions are sus-
pended.
 VDC function
 TCS function
 ABS function
 EBD function
 hill start assist function
 Brake limited slip differential (BLSD) function
C1121 When a malfunction is detec
ted in front LH ABS OUT valve.
C1122 When a malfunction is detected in front RH ABS IN valve.
C1123 When a malfunction is det ected in front RH ABS OUT valve.
C1124 When a malfunction is detected in rear LH ABS IN valve.
C1125 When a malfunction is detected in rear LH ABS OUT valve.
C1126 When a malfunction is det ected in rear RH ABS IN valve.
C1127 When a malfunction is detected in rear RH ABS OUT valve.
C1130 When a malfunction is detected in ECM system. The following functions are sus-
pended.
 VDC function
 TCS function
 hill start assist function
 Brake limited slip differential
(BLSD) function
C1140 When a malfunction is detected in actuator relay. The following functions are sus-
pended.
 VDC function
 TCS function
 ABS function
 EBD function
 hill start assist function
 Brake limited slip differential
(BLSD) function
C1142
*2When a malfunction is detected in master cylinder pressure sensor or control pres-
sure sensor. The following functions are sus-
pended.
 VDC function
 TCS function
 hill start assist function
 Brake limited slip differential
(BLSD) function
C1143 When a malfunction is detected in steering angle sensor.
C1144 When neutral position adjustment of steering angle sensor is not complete.
C1145
 When a malfunction is detected in yaw rate signal.
 When yaw rate signal is not continuously received for 2 seconds or more.
 When side G signal is not continuously received for 2 seconds or more.
 When decel G signal is not continuously received for 2 seconds or more.
The following functions are sus-
pended.
 VDC function
 TCS function
 ABS function
 hill start assist function
 Brake limited slip differential
(BLSD) function
C1146 When a malfunction is detected in side/decel G signal.
C1155
 When brake fluid level low signal is detected.
 When an open circuit is detected in brake fluid level switch circuit.
C1160 When calibration of yaw rate/side/decal G sensor is not complete.
C1164 When a malfunction is detected in cut valve 1. The following functions are sus- pended.
 VDC function
 TCS function
 ABS function
 EBD function
 hill start assist function
 Brake limited slip differential (BLSD) function
C1165 When a malfunction is detected in cut valve 2.
C1166 When a malfunction is detected in suction valve 1.
C1167 When a malfunction is detected in suction valve 2.
C1170 When the informatio
n in ABS actuator and electric unit (control unit) is not the same.The following functions are sus-
pended.
 VDC function
 TCS function
 ABS function
 hill start assist function
 Brake limited slip differential
(BLSD) function
DTC Malfunction detected condition Fail-safe condition
Revision: 2010 May2011 QX56

BRC-28
< SYSTEM DESCRIPTION >[WITH VDC]
SYSTEM
*1: Models with 4WD System
*2: Models with Advanced Driver Assistance System
Protection FunctionINFOID:0000000006228185
The VDC warning lamp, ABS warning lamp and brake warning lamp turns ON and DTC “C118E” may be
detected in self-diagnosis result of “ABS” when the br
ake pedal is excessively operated, such as air bleeding.
This is not a system malfunction because this occurs due to the temporary decrease in accumulator fluid pres-
sure. The system returns to normal condition when the accu mulator fluid pressure reaches the specified pres-
sure with the ignition switch ON and the VDC warning lamp, ABS warning lamp, and brake warning lamp turn
OFF. After these steps, erase self-diagnos is results for “ABS” with CONSULT-III.
NOTE:
D T C “ C 1111 ” i s d e t e c t e d i n s e l f - d i agnosis results of “ABS” when the a ccumulator system has a malfunction.
VDC FUNCTION
VDC FUNCTION : System DescriptionINFOID:0000000006222572
 Side slip or tail slip may occur while driving on a slippery road or intending an urgent evasive driving. VDC
function detects side slip status using each sensor when side slip or tail slip is about to occur and improves
vehicle stability by brake control and engine output control during driving.
 In addition to ABS function, EBD function and TCS functi on, target side slip amount is calculated according
to steering operation amount from steering angle sensor and brake operation amount from pressure sensor.
By comparing this information with vehicle side slip amount that is calculated from information from yaw rate/
C118EWhen performing excessive brake pedal operation with the vehicle stopped. [When
accumulator fluid pressure reaches 11.43 MPa (114 bar, 116.6 kg/cm2, 1657 psi) af-
ter reaching 17.3 MPa (173 bar, 176.5 kg/cm2, 2509 psi.] The following functions are sus-
pended.
 VDC function
 TCS function
 ABS function
 EBD function
 hill start assist function
 Brake limited slip differential
(BLSD) function
U1000 When CAN communication signal is not continuously received for 2 seconds or
more. The following functions are sus-
pended.
 VDC function
 TCS function
 ABS function
 hill start assist function
 Brake limited slip differential
(BLSD) function
DTC Malfunction detected condition Fail-safe condition
DTC
 VDC warning lamp
 ABS warning lamp
 Brake warning lamp
Condition Description protection function
C118E ON When temporary decrease in accumulator fluid pres-
sure.
NOTE:
System is not malfunction. The following functions are suspended
temporarily
 VDC function
 TCS function
 ABS function
 EBD function
 hill start assist function
 Brake limited slip differential (BLSD)
function
Revision: 2010 May2011 QX56

BRC-30
< SYSTEM DESCRIPTION >[WITH VDC]
SYSTEM
Major signal transmission between each unit via communication lines is shown in the following table.
*1: Communication line between yaw rate/side/decal G s
ensor and ABS actuator and electric unit (control unit)
*2: Models with 4WD system
OPERATION CHARACTERISTICS
VDC Function That Prevents Oversteer Tendency
 During a cornering, brake force (brake fluid pressure) is applied on front wheel and rear wheel on the outer side of turn. Moment directing towards the outer side of turn is generated. Oversteer is prevented.
 Changing driving lane on a slippery road, when oversteer tendency is judged large, engine output is con- trolled as well as brake force (brake fluid pr essure) of 4 wheels. Oversteer tendency decreases.
VDC Function That Prevents Understeer Tendency
Component Signal description
Yaw rate/side/decel G sensor Mainly transmits the following si
gnals to ABS actuator and electric unit (control unit) via com-
munication line
*1.
 Yaw rate signal
 Side G sensor signal
 Decel G sensor signal
ECM Mainly transmits the following si
gnals to ABS actuator and electric 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 si
gnals to ABS actuator and electric unit (control unit) via CAN
communication.
 Shift position signal
Transfer control unit
*2Mainly transmits the following si gnals to ABS actuator and electric unit (control unit) via CAN
communication.
 Current 4WD mode signal
Steering angle sensor Mainly transmits the following si
gnals to ABS actuator and electric unit (control unit) via CAN
communication.
 Steering angle sensor signal
Combination meter Mainly receives
the following signals from ABS actuator and electric unit (control unit) via CAN
communication.
 VDC warning lamp signal
 VDC OFF indicator lamp
JPFIC0135GB
JPFIC0136GB
Revision: 2010 May2011 QX56

SYSTEMBRC-31
< SYSTEM DESCRIPTION > [WITH VDC]
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 During a cornering, brake force (brake fluid pressu re) is applied on front wheel and rear wheel on the inner
side of turn. Moment directing towards the inner side of turn is generated. Understeer is prevented.
 Applying braking during a cornering on a slippery road, when understeer tendency is judged large, engine
output is controlled as well as brake force (brake fluid pressure) of four wheels. Understeer tendency
decreases.
TCS FUNCTION
TCS FUNCTION : System DescriptionINFOID:0000000006222573
 Wheel spin status of drive wheel is detected by wheel sensor of 4
wheels. Engine output and transmission shift status is controlled
so that slip rate of drive wheels is in appropriate level. When wheel
spin occurs on drive wheel, ABS ac tuator and electric unit (control
unit) perform brake force control of LH and RH drive wheels (apply
brake force by increasing brake fluid pressure of drive wheel) and
decrease engine torque by engine torque control. Wheel spin
amount decreases. Engine torque is controlled to appropriate
level.
 TCS function can be switched to non-operational status (OFF) by
operating VDC OFF switch. In this case, VDC OFF indicator lamp
turns ON.
 TCS function is not operate when 4WD mode is “4L”. (Models with
4WD system)
 VDC warning lamp blinking while TCS function is in operation and indicates to the driver that the function is in operation.
 Slight vibrations are felt on the brake pedal and the operation noises occur, when TCS function operates. This is not a malfunc-
tion because it is caused by TCS function that is normally oper-
ated.
 CONSULT-III can be used to diagnose the system diagnosis.
 Fail-safe function is adopted. W hen a malfunction occurs in TCS
function, the control is suspended for VDC function, TCS function,
hill start assist function and brake limited slip differential (BLSD)
function. The vehicle status becomes the same as models without VDC function, TCS function, hill start
assist function and brake limited slip differential (B LSD) function. However, ABS function and EBD function
are operated normally. Refer to BRC-25, "
Fail-safe".
SYSTEM DIAGRAM
NOTE:
JPFIC0137GB
JPFIC0138GB
JPFIC0139GB
Revision: 2010 May2011 QX56

BRC-34
< SYSTEM DESCRIPTION >[WITH VDC]
SYSTEM
Transfer control unit is appli
ed to models with 4WD system.
INPUT SIGNAL AND OUTPUT SIGNAL
Major signal transmission between each unit via communication lines is shown in the following table.
*1: Communication line between yaw rate/side/decal G s ensor and ABS actuator and electric unit (control unit)
*2: Models with 4WD system
EBD FUNCTION
EBD FUNCTION : System DescriptionINFOID:0000000006222575
 By preventing rear wheel slip increase through rear wheel brake force (brake fluid pressure) control that is
electronically controlled when slight skip on front and r ear wheels are detected during braking, stability dur-
ing braking is improved.
JPFIC0184GB
Component Signal description
Yaw rate/side/decel G sensor Mainly transmits the following si
gnals to ABS actuator and electric unit (control unit) via com-
munication line
*1.
 Yaw rate signal
 Side G sensor signal
 Decel G sensor signal
Transfer control unit
*2Mainly transmits the following si gnals to ABS actuator and electric unit (control unit) via CAN
communication.
 Current 4WD mode signal
Combination meter Mainly receives
the following signals from ABS actuator and electric unit (control unit) via CAN
communication.
 ABS warning lamp signal
Revision: 2010 May2011 QX56

SYSTEMBRC-35
< SYSTEM DESCRIPTION > [WITH VDC]
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 EBD function is expanded and developed from conventi onal ABS function and corrects rear wheel brake
force to appropriate level by electronic control according to load weight (number of passengers).
 During braking, control unit portion compares slight slip on front and rear wheels by wheel speed sensor signal, transmits drive sig-
nal to actuator portion when rear wheel slip exceeds front wheel
slip for the specified value or more, and controls rear wheel brake
force (brake fluid pressure) so t hat increase of rear wheel slip is
prevented and slips on front wheel and rear wheel are nearly
equalized. ABS control is applied when slip on each wheel
increases and wheel speed is the threshold value of ABS control or
less.
 CONSULT-III can be used to diagnose the system diagnosis.
 Fail-safe function is adopted. When a malfunction occurs in EBD function, the control is suspended for VDC function, TCS function,
ABS function, EBD function, hill start assist function and brake lim-
ited slip differential (BLSD) func tion. The vehicle status becomes
the same as models without VDC function, TCS function, ABS
function, EBD function, hill start assist function and brake limited
slip differential (BLSD) function. Refer to BRC-25, "
Fail-safe".
JPFIC0142GB
JPFIC0143GB
Revision: 2010 May2011 QX56

BRC-36
< SYSTEM DESCRIPTION >[WITH VDC]
SYSTEM
SYSTEM DIAGRAM
INPUT SIGNAL AND OUTPUT SIGNAL
Major signal transmission between each unit via communication lines is shown in the following table.
hill start assist FUNCTION
hill start assist FUNCTION : System DescriptionINFOID:0000000006222576
 This function maintains brake fluid pressure so that
the vehicle does not move backwards even if brake
pedal is released to depress accelerator pedal to start the vehicle while it is stopped on an uphill slope by
depressing brake pedal.
 This function operates when the vehicle is in stop status on a uphill slope of slope ratio 10% or more and
selector lever is in the position other than P or N.
 hill start assist function is only for the start aid. It maintains the brake fluid pressure for approx. 2 seconds after releasing the brake pedal, and then decreases the pressure gradually. If the vehicle can start by the
accelerator operation, the brake is released automatically and a smooth start can be performed.
 Fail-safe function is adopted. When a malfunction occurs in hill start assist function, the control is suspended
for VDC function, TCS function, hill start assist func tion and brake limited slip differential (BLSD) function.
The vehicle status becomes the same as models without VDC function, TCS function, hill start assist func-
tion and brake limited slip differential (BLSD) functi on. However, ABS function and EBD function are oper-
ated normally. Refer to BRC-25, "
Fail-safe".
JPFIC0144GB
Component Signal description
Combination meter Mainly receives
the following signals from ABS actuator and electric unit (control unit) via CAN
communication.
 Brake warning lamp signal
Revision: 2010 May2011 QX56

BRC-42
< SYSTEM DESCRIPTION >[WITH VDC]
DIAGNOSIS SYSTEM [
ABS ACTUATOR AND ELECTRIC UNIT (CONTROL
UNIT)]
Note 1: Refer to BRC-16, "System Description" for ON/OFF conditions of each warning lamp and indicator
lamp.
Note 2: Models with 4WD System
Note 3: Models with Advanced Driver Assistance System
Note 4: USS means “hill start assist”
ACTIVE TEST
The active test is used to determine and identify details of a malfunction, based on self-diagnosis test result
sand data obtained in the DATA MONITOR. In response to instructions from CONSULT-III, instead of those
SV2
(On/Off) Suction valve 2 operation status is displayed.
STOP LAMP SW2
(On/Off) Stop lamp switch signal input status is displayed.
ACCEL POS SIG
(%) ×
Displays the Accelerator pedal position
SIDE G-SENSOR
(m/s
2) ×
Side G detected by side G sensor is displayed.
STR ANGLE SIG
( ° ) ×
Steering angle detected by steering angle sensor is dis-
played.
PRESS SENSOR
(bar) ×Detects the brake fluid pressure of master cylinder part is
displayed.
ACCUM PRESS SEN
(bar) Detects the brake fluid pressure of accumulator is dis-
played.
CONT PRESS SEN
(Note 3)
(bar) Detects the brake fluid pressure of control pressure sensor
is displayed
EBD SIGNAL
(On/Off) EBD operation status is displayed.
ABS SIGNAL
(On/Off) ABS operation status is displayed.
TCS SIGNAL
(On/Off) TCS operation status is displayed.
VDC SIGNAL
(On/Off) VDC operation status is displayed.
EBD FAIL SIG
(On/Off) EBD fail-safe signal status is displayed.
ABS FAIL SIG
(On/Off) ABS fail-safe signal st
atus is displayed.
TCS FAIL SIG
(On/Off) TCS fail-safe signal status is displayed.
VDC FAIL SIG
(On/Off) VDC fail-safe signal status is displayed.
CRANKING SIG
(On/Off) Cranking status is displayed.
FLUID LEV SW
(On/Off) ×Brake fluid level signal input status via CAN communication
is displayed.
PARK BRAKE SW
(On/Off) ×Parking brake switch signal input status via CAN communi-
cation is displayed.
STP ON RLY
(On/Off) Stop lamp switch relay status is displayed.
USS SIG
(Note 4)
(On/Off) hill start assist operation status is displayed.
Item (Unit)
Monitor item selection
Note
INPUT SIGNALS MAIN ITEMS
Revision: 2010 May2011 QX56

ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)BRC-47
< ECU DIAGNOSIS INFORMATION > [WITH VDC]
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Note 1: Confirm tire pressure is standard value.
Note 2: Refer to BRC-16, "
System Description" for ON/Blinking/OFF conditions of each warning lamp and indi-
cator lamp.
Note 3: Models with 4WD System
Note 4: Models with Advanced Driver Assistance System
Note 5: USS means “hill start assist”.
Fail-safeINFOID:0000000006222580
VDC FUNCTION, TCS FUNCTION, hill start assi st FUNCTION AND BRAKE LIMITED SLIP DIFFER-
ENTIAL (BLSD) FUNCTION
VDC warning lamp in combination meter turn ON w hen a malfunction occurs in system [ABS actuator and
electric unit (control unit)]. The control is suspended for VDC function, TCS function, hill start assist function
and brake limited slip differential (BLSD) function. T he Vehicle status becomes the same as models without
PRESS SENSORBrake pedal not depressed Approx. 0 bar
Brake pedal depressed (
−40) – (+300) bar
ACCUM PRESS SEN With ig nition switch ON Approx. 0 – 210 bar (Proportional to the
amount of accumulated pressure in the
accumulator)
CONT PRESS SEN
(Note 4)Brake pedal not depressed Approx. 0 bar
Brake pedal depressed ( −40) – (+300) bar
EBD SIGNAL EBD is active On
EBD is inactive Off
ABS SIGNAL ABS is active On
ABS is inactive Off
TCS SIGNAL TCS is active On
TCS is inactive Off
VDC SIGNAL VDC is active On
VDC is inactive Off
EBD FAIL SIG In EBD fail-safe On
EBD is normal Off
ABS FAIL SIG In ABS fail-safe On
ABS is normal Off
TCS FAIL SIG In TCS fail-safe On
TCS is normal Off
VDC FAIL SIG In VDC fail-safe On
VDC is normal Off
CRANKING SIG At cranking On
Other than at cranking Off
FLUID LEV SW When brake fluid level switch is ON (brake fluid level
is less than the specified level)
On
When brake fluid level switch is OFF Off
PARK BRAKE SW When parking brake is active On
Parking brake is released Off
STP ON RLY Stop lamp relay is active On
Stop lamp relay is inactive Off
USS SIG
(Note 5)hill start assist is active On
hill start assist is inactive Off
Monitor item Condition Reference values in normal operation
Revision: 2010 May2011 QX56