INFINITI QX56 2011 Factory Service Manual

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

SYSTEMBRC-37
< SYSTEM DESCRIPTION > [WITH VDC]
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SYSTEM DIAGRAM
INPUT SIGNAL AND OUTPUT SIGNAL
Major signal transmission between each unit via communication lines is shown in the following table.
*: Communication line between yaw rate/side/decal G s ensor and ABS actuator and electric unit (control unit)
BRAKE LIMITED SLIP DIFFERENTIAL (BLSD) FUNCTION
BRAKE LIMITED SLIP DIFFERENTIAL (BLSD) FUNCTION : System Description
INFOID:0000000006222577
 LH and RH driving wheel spin is always monitored. If necessary, appropriate brake force is independently
applied to LH or RH driving wheel so that one-sided wheel spin is avoided and traction is maintained. Mainly
starting ability is improved.
JPFIC0145GB
Component Signal description
Yaw rate/side/decel G sensor Mainly transmits the following signals to ABS actuator and electric unit (control unit) via com-
munication line *.
 Yaw rate signal
 Side G sensor signal
 Decel G sensor signal
ECM Mainly transmits the following signals 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 signals to ABS actuator and electric unit (control unit) via CAN
communication.
 Shift position 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 signal
Revision: 2010 May2011 QX56

BRC-38
< SYSTEM DESCRIPTION >[WITH VDC]
SYSTEM
 Brake limited slip differential (BLSD) function operates
while VDC function is in non-operational status (OFF)
by VDC OFF switch.
 VDC warning lamp blinking while brake limited slip di fferential (BLSD) 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 brake limited slip differen-
tial (BLSD) function operates. This is not a malfunction because it is caused by brake limited slip differential
(BLSD) function that is normally operated.
 Fail-safe function is adopted. When a malfunction occurs in brake limited slip differential (BLSD) function,
the control is suspended for VDC function, TCS function, hi ll start assist function and brake limited slip differ-
ential (BLSD) function. The vehicle status becomes the same as models without VDC function, TCS func-
tion, hill start assist function and brake limited slip di fferential (BLSD) function. However, ABS function and
EBD function are operated normally. Refer to BRC-25, "
Fail-safe".
SYSTEM DIAGRAM
NOTE:
Transfer control unit is applied 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.
JPFIC0183GB
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
Revision: 2010 May2011 QX56

SYSTEMBRC-39
< SYSTEM DESCRIPTION > [WITH VDC]
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*1: Communication line between yaw rate/side/decal G s ensor and ABS actuator and electric unit (control unit)
*2: Models with 4WD system
Transfer control unit*2Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN
communication.
 Current 4WD mode signal
Steering angle sensor Mainly transmits the following signals 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
Component Signal description
Revision: 2010 May2011 QX56

BRC-40
< SYSTEM DESCRIPTION >[WITH VDC]
DIAGNOSIS SYSTEM [
ABS ACTUATOR AND ELECTRIC UNIT (CONTROL
UNIT)]
DIAGNOSIS SYSTEM [ABS ACTUATOR AND ELECTRIC UNIT (CONTROL
UNIT)]
CONSULT-III FunctionINFOID:0000000006222578
APPLICATION ITEMS
CONSULT-III can display each diagnostic item using the diagnostic test modes as follows.
*: The following diagnosis information is erased by erasing.
DTC
 Freeze frame data (FFD)
ECU IDENTIFICATION
ABS actuator and electric unit (cont rol unit) part number can be read.
SELF DIAGNOSTIC RESULT
Refer to BRC-51, "DTC Index".
When “CRNT” is displayed on self-diagnosis result,
 The system is presently malfunctioning.
When “PAST” is displayed on self-diagnosis result, System malfunction in the past is detect ed, but the system is presently normal.
Freeze frame data (FFD)
DATA MONITOR
×: Applicable
Mode Function description
ECU identification Parts number of ABS actuator and electric unit (control unit) can be read.
Self Diagnostic Result Self-diagnostic results and freeze frame data can be read and erased quickly.
*
DATA MONITOR Input/Output data in the ABS actuator and electric unit (control unit) can be read.
ACTIVE TEST Diagnostic Test Mode in
which CONSULT-III drives some act uators apart from the ABS actuator and
electric unit (control unit) and also shifts some parameters in a specified range.
WORK SUPPORT Components can be quickly and accurately adjusted.
Item name Display item
IGN counter
(0 − 39) The number of times that ignition switch is tu
rned ON after the DTC is detected is displayed.
 When “0” is displayed: It indicates that the system is presently malfunctioning.
 When except “0” is displayed: It indicates that system malfunction in the past is detected, but the system is pres- ently normal.
NOTE:
Each time when ignition switch is turned OFF to ON, numerical number increases in 1 → 2 → 3...38 → 39. When
the operation number of times exceeds 39, the number do not increase and “39” is displayed until self-diagnosis
is erased.
Item (Unit) Monitor item selection
Note
INPUT SIGNALS MAIN ITEMS
FR LH SENSOR
[km/h (MPH)] ××Wheel speed calculated by front LH wheel sensor is dis-
played.
FR RH SENSOR
[km/h (MPH)] ××Wheel speed calculated by front RH wheel sensor is dis-
played.
RR LH SENSOR
[km/h (MPH)] ××
Wheel speed calculated by rear LH wheel sensor is dis-
played.
RR RH SENSOR
[km/h (MPH)] ××Wheel speed calculated by rear RH wheel sensor is dis-
played.
DECEL G-SEN
(G) ××
Decel G detected by decel G sensor is displayed.
Revision: 2010 May2011 QX56

DIAGNOSIS SYSTEM [ABS ACTUATOR AND ELECTRIC UNIT (CONTROL
UNIT)]
BRC-41
< SYSTEM DESCRIPTION > [WITH VDC]
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FR RH IN SOL
(On/Off) ×Operation status of front
RH wheel ABS IN valve is dis-
played.
FR RH OUT SOL
(On/Off) ×Operation status of front
RH wheel ABS OUT valve is dis-
played.
FR LH IN SOL
(On/Off) ×
Operation status of front LH wheel ABS IN valve is dis-
played.
FR LH OUT SOL
(On/Off) ×Operation status of front LH wheel ABS OUT valve is dis-
played.
RR RH IN SOL
(On/Off) ×
Operation status of rear RH wh eel ABS IN valve is displayed
RR RH OUT SOL
(On/Off) ×
Operation status of rear RH wheel ABS OUT valve is dis-
played.
RR LH IN SOL
(On/Off) ×Operation status of rear LH
wheel ABS IN valve is dis-
played.
RR LH OUT SOL
(On/Off) ×Operation status of rear LH
wheel ABS OUT valve is dis-
played.
EBD WARN LAMP
(On/Off) Brake warning lamp ON/OFF status is displayed.
(Note 1)
STOP LAMP SW
(On/Off)××
Stop lamp switch signal input status is displayed.
MOTOR RELAY
(On/Off) ×
ABS motor and motor relay status is displayed.
ACTUATOR RLY
(On/Off) ×
ABS actuator relay status is displayed.
ABS WARN LAMP
(On/Off) ×
ABS warning lamp ON/OFF status is displayed.
(Note 1)
OFF LAMP
(On/Off) ×
VDC OFF indicator lamp ON/OFF status is displayed.(Note 1)
OFF SW
(On/Off) ××
VDC OFF switch signal input status is displayed.
SLIP/VDC LAMP
(On/Off) ×
VDC warning lamp ON/OFF status is displayed.
(Note 1)
BATTERY VOLT
(V) ××Voltage supplied to ABS actuator and electric unit (control
unit) is displayed.
GEAR ××Current gear position judged from current gear position sig-
nal is displayed.
ENGINE SPEED
(tr/min) ××
Engine speed status is displayed.
YAW RATE SEN
(d/s) ××
Yaw rate detected by yaw rate sensor is displayed.
R POSI SIG
(On/Off) R range signal input status judged from R range signal is
displayed.
4WD MODE MON
(Note 2)
(AUTO/LOCK/##) ××
4WD control status is displayed.
N POSI SIG
(On/Off) N range signal input status judged from N range signal is
displayed.
CV1
(On/Off) Cut valve 1 operation status is displayed.
CV2
(On/Off) Cut valve 2 operation status is displayed.
SV1
(On/Off) Suction valve 1 operation status is displayed.
Item (Unit)
Monitor item selection
Note
INPUT SIGNALS MAIN ITEMS
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

DIAGNOSIS SYSTEM [ABS ACTUATOR AND ELECTRIC UNIT (CONTROL
UNIT)]
BRC-43
< SYSTEM DESCRIPTION > [WITH VDC]
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from ABS actuator and electric unit (control unit) on the vehi cle, a drive signal is sent to the actuator to check
its operation.
CAUTION:
 Never perform ACTIVE TEST while driving the vehicle.
 Always bleed air from brake system before active test.
 Never perform active test when system is malfunctioning.
NOTE:
 When active test is performed while depressing the pedal, the pedal depressing stroke may change. This is
not a malfunction.
 “TEST IS STOPPED” is displayed approx. 10 seconds after operation start.
 When performing active test again after “TEST IS STOPPED” is displayed, select “BACK”.
 ABS warning lamp, brake warning lamp and VDC warning lamp may turn ON during active test. This is not a malfunction.
ABS IN Valve and ABS OUT Valve
When “Up”, “Keep” or “Down” is selected on display scr een, the following items are displayed when system is
normal.
*: Immediately after being selected, status is “O n”. Status changes to “Off” after approx. 2 seconds.
ABS IN Valve (ACT) and ABS OUT Valve (ACT)
When “Up”, “ACT KEEP” or “ACT UP” is selected on display screen, the following items are displayed when
system is normal.
Test item Display Item Display
Up Keep Down
FR RH SOL FR RH IN SOL Off On* On*
FR RH OUT SOL Off Off On*
FR LH SOL FRLH IN SOL Off On* On*
FR LH OUT SOL Off Off On*
RR RH SOL RR RH IN SOL Off On* On*
RR RH OUT SOL Off Off On*
RR LH SOL RR LH IN SOL Off On* On*
RR LH OUT SOL Off Off On*
Test item Display Item Display
Up ACT KEEP ACT UP
FR RH SOL (ACT) FR RH IN SOL Off Off On*
FR RH OUT SOL Off Off Off
CV1 Off On* On*
SV1 Off Off On*
FR LH SOL (ACT) FR LH IN SOL Off Off On*
FR LH OUT SOL Off Off Off
CV1 Off On* On*
SV1 Off Off On*
RR RH SOL (ACT) RR RH IN SOL Off Off On*
RR RH OUT SOL Off Off Off
CV2 Off On* On*
SV2 Off Off On*
RR LH SOL (ACT) RR LH IN SOL Off Off On*
RR LH OUT SOL Off Off Off
CV2 Off On* On*
SV2 Off Off On*
Revision: 2010 May2011 QX56