2011 INFINITI QX56 differential

BRC-26
< SYSTEM DESCRIPTION >[WITH VDC]
SYSTEM
ABS FUNCTION
ABS warning lamp and VDC warning lamp in combinati
on meter turn ON when a malfunction occurs in system
[ABS actuator and electric unit (control unit)]. The c ontrol is suspended for VDC function, TCS function, ABS
function, hill start assist function and brake limited sl ip differential (BLSD) function. The vehicle status
becomes the same as models without VDC function, TCS f unction, ABS function, hill start assist function and
brake limited slip differential (BLSD) function. However, EBD function is operated normally.
NOTE:
ABS self-diagnosis sound may be heard the same as in the normal condition, because self-diagnosis is per-
formed when ignition switch turns ON and when vehicle initially starts.
EBD FUNCTION
ABS warning lamp, brake warning lamp and VDC warning lamp in combination meter turn ON when a mal-
function occurs in system [ABS actuator and electric unit (control unit)]. The control is suspended for VDC
function, TCS function, ABS function, EBD function, hill start assist function and brake limited slip differential
(BLSD) function. The vehicle status becomes the sa me as models without VDC function, TCS function, ABS
function, EBD function, hill star t assist function and brake limited slip differential (BLSD) function.
DTC Malfunction detected condition Fail-safe condition
C1101 When an open circuit is detected in rear RH wheel sensor circuit.
The following functions are sus-
pended.
 VDC function
 TCS function
 ABS function
 EBD function (only when both 2 rear wheels are malfunctioning)
 hill start assist function
 Brake limited slip differential
(BLSD) function
C1102 When an open circuit is detected in rear LH wheel sensor circuit.
C1103 When an open circuit is detected in front RH wheel sensor circuit.
C1104 When an open circuit is detected in front LH wheel sensor circuit.
C1105
 When power supply voltage of rear RH wheel sensor is low.
 When distance between rear RH wheel sensor and rear RH wheel sensor rotor is
large.
 When installation of rear RH wheel sensor or rear RH wheel sensor rotor is not
normal.
C1106  When power supply voltage of rear LH wheel sensor is low.
 When distance between rear LH wheel sensor and rear LH wheel sensor rotor is
large.
 When installation of rear LH wheel sensor or rear LH wheel sensor rotor is not nor- mal.
C1107  When power supply voltage of front RH wheel sensor is low.
 When distance between front RH wheel sensor and front RH wheel sensor rotor
is large.
 When installation of front RH wheel sensor or front RH wheel sensor rotor is not normal.
C1108  When power supply voltage of front LH wheel sensor is low.
 When distance between front LH wheel sensor and front LH wheel sensor rotor is
large.
 When installation of front LH wheel sensor or front LH wheel sensor rotor is not normal.
C1109  When ignition voltage is 10 V or less.
 When ignition voltage is 16 V or more. The following functions are sus-
pended.
 VDC function
 TCS function
 ABS function
 EBD function
 hill start assist function
 Brake limited slip differential
(BLSD) function
C 1111
 When a malfunction is detected in motor or motor relay.
 When a low pressure malfunction is detected in accumulator.
 When a malfunction is detected in accumulator pressure sensor.
C 111 5 When difference in wheel speed between any wheel and others is detected during
the vehicle is driven, because of installation of other tires than specified. The following functions are sus-
pended.
 VDC function
 TCS function
 ABS function
 hill start assist function
 Brake limited slip differential
(BLSD) function
C 111 6
 When stop lamp switch signal is not input when brake pedal depress.
 When stop lamp switch signal is not input when stop lamp relay operates.
C 111 8
*1When a malfunction is detected in transfer control unit system.
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

SYSTEMBRC-29
< SYSTEM DESCRIPTION > [WITH VDC]
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side/decel G- sensor and wheel sensor, vehicle drivi ng conditions (conditions of understeer or oversteer) are
judged and vehicle stability is improved by brake forc e control on all 4 wheels and engine output control.
 Control unit portion automatically improves driving st ability by performing brake force control as well as
engine output control, by transmitting drive signal to actuator portion according to difference between target
side slip amount and vehicle side slip amount
 VDC function can be switched to non-operational status (OFF) by operating VDC OFF switch. In this case,
VDC OFF indicator lamp turns ON.
 VDC function is not operate when 4WD mode is “4L”. (Models with 4WD system)
 VDC warning lamp blinking while VDC function is in oper ation and indicates to the driver that the function is
in operation.
 Slight vibrations are felt on the brake pedal and t he operation noises occur, when VDC function operates.
This is not a malfunction because it is caus ed by VDC function that is normally operated.
 CONSULT-III can be used to diagnose the system diagnosis.
 Fail-safe function is adopted. When a malfunction occurs in VDC function, the control is suspended for VDC
function, TCS function, hill start as sist function and brake limited slip di fferential (BLSD) function. The vehi-
cle status becomes the same as m odels without VDC function, TCS functi on, hill start assist function and
brake limited slip differential (BLSD) function. Ho wever, ABS function and EBD function are operated nor-
mally. Refer to BRC-25, "
Fail-safe".
NOTE:
VDC has the characteristic as de scribed here, but it is not the device that helps reckless driving.
SYSTEM DIAGRAM
NOTE:
Transfer control unit is applied to models with 4WD system.
INPUT SIGNAL AND OUTPUT SIGNAL
JPFIC0133GB
JPFIC0183GB
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

SYSTEMBRC-33
< SYSTEM DESCRIPTION > [WITH VDC]
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ABS FUNCTION : System DescriptionINFOID:0000000006222574
 By preventing wheel lock through brake force (brake flui d pressure) control that is electronically controlled by
detecting wheel speed during braking, stability during em ergency braking is improved so that obstacles can
be easily bypassed by steering operation.
 During braking, control units calculates wheel speed and pseudo-vehicle speed, and transmits pressure
increase, hold or decrease signals to actuator portion according to wheel slip status.
 The following effects are obtained by preventing wheel lock during
braking.
- Vehicle tail slip is prevented during braking when driving straight.
- Understeer and oversteer tendencie s are moderated during brak-
ing driving on a corner.
- Obstacles may be easily bypassed by steering operation during braking.
 Slight vibrations are felt on the brake pedal and the operation noises occur, when ABS function oper ates. This is not a malfunc-
tion because it is caused by ABS function that is normally oper-
ated.
 CONSULT-III can be used to diagnose the system diagnosis.
 Fail-safe function is adopted. When a malfunction occurs in ABS 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, ABS func tion, hill start assist function
and brake limited slip differential (BLSD) function. However, EBD
function is operated normally. Refer to BRC-25, "
Fail-safe".
NOTE:
 ABS has the characteristic as described here, but it is not the device that helps reckless driving.
 To stop vehicle efficiently, ABS does not operate and ordinary brake operates at low speed [approx. 5 to 10 km/h (3.1 to 6.2
MPH) or less, but differs subject to road conditions).
 Self-diagnosis is performed immediately after when engine starts and when vehicle initially is driven [by vehi-
cle speed approx. 15 km/h (9.3 MPH)]. Motor sounds are generated during self-diagnosis. In addition, brake
pedal may be felt heavy when depressing brake pedal lightly. These symptoms are not malfunctions.
SYSTEM DIAGRAM
NOTE:
JPFIC0140GB
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