2011 INFINITI QX56 Eco

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

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

BRC-44
< SYSTEM DESCRIPTION >[WITH VDC]
DIAGNOSIS SYSTEM [
ABS ACTUATOR AND ELECTRIC UNIT (CONTROL
UNIT)]
*: Immediately after being selected, status is “O n”. Status changes to “Off” after approx. 2 seconds.
Stop Lamp ON Relay
When “On” or “Off” is selected on display screen, t he following items are displayed when system is normal.
NOTE:
Display occasionally changes On/Off for a moment after ignition switch is turned ON. This is operation for
checking purposes and is not a malfunction.
WORK SUPPORT
Test item Display Item Display
On Off
STOP LAMP ON RELAY STOP LAMP ON RELAY On Off
Conditions Description
ST ANGLE SENSOR ADJUSTMENT Perform neutral position adjustment of steering angle sensor.
DECEL G SENSOR CALIBRATION Perform decel G sensor calibration.
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

BRC-48
< ECU DIAGNOSIS INFORMATION >[WITH VDC]
ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)
VDC function, TCS function, hill start assist function and
brake limited slip differential (BLSD) function. How-
ever, ABS function and EBD function are operated normally.
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.
Revision: 2010 May2011 QX56

ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)BRC-49
< ECU DIAGNOSIS INFORMATION > [WITH VDC]
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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.
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. DTC Malfunction detected condition Fail-safe condition
Revision: 2010 May2011 QX56

BRC-50
< ECU DIAGNOSIS INFORMATION >[WITH VDC]
ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)
*1: Models with 4WD System
*2: Models with Advanced Driver Assistance System
Protection FunctionINFOID:0000000006222581
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.
DTC Inspection Priority ChartINFOID:0000000006222582
When multiple DTCs are displayed simultaneously, check one by one depending on the following priority list.
C1170 When the information 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
C118E When performing excessive brake pedal operation with the vehicle stopped. [When
accumulator fluid pressure reaches 11.43 MPa (114 bar, 116.6 kg/cm
2, 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
Priority Detected item (DTC)
1  U1000 CAN COMM CIRCUIT
2  C1170 VARIANT CODING
Revision: 2010 May2011 QX56

BRC-60
< BASIC INSPECTION >[WITH VDC]
DIAGNOSIS AND REPAIR WORK FLOW
BASIC INSPECTION
DIAGNOSIS AND REPAIR WORK FLOW
Work FlowINFOID:0000000006222585
DETAILED FLOW
1.INTERVIEW FROM THE CUSTOMER
Clarify customer complaints before inspection. First of all, perform an interview utilizing BRC-61, "
Diagnostic
Work Sheet" and reproduce the symptom as well as fully under stand it. Ask customer about his/her complaints
carefully.Check symptoms by driving vehicle with customer, if necessary.
CAUTION:
Customers are not professional. Never guess easily like “maybe the customer means that...,” or “
maybe the customer mentions this symptom”.
>> GO TO 2.
2.CHECK SYMPTOM
Reproduce the symptom that is indicated by the customer, based on the information from the customer
obtained by interview. Also check that the sympt om is not caused by fail-safe mode. Refer to BRC-47, "
Fail-
safe".
CAUTION:
When the symptom is caused by normal operation, fully inspect each portion and obtain the under-
standing of customer that the sympt om is not caused by a malfunction.
>> GO TO 3.
3.PERFORM THE SELF-DIAGNOSIS
With CONSULT-III.
Perform self-diagnosis for “ABS”.
Is DTC detected?
YES >> Record or print self-diagnosis results. GO TO 4.
NO >> GO TO 6.
4.RECHECK THE SYMPTOM
With CONSULT-III.
1. Erase self-diagnostic results for “ABS”.
2. Perform DTC confirmation procedures for the error-detected system. NOTE:
If some DTCs are detected at the some time, det ermine the order for performing the diagnosis based on
BRC-50, "
DTC Inspection Priority Chart" [ABS actuator and electric unit (control unit)].
Is any DTC detected?
YES >> GO TO 5.
NO >> Check harness and connectors based on the information obtained by interview. Refer to GI-40,
"Intermittent Incident".
5.REPAIR OR REPLACE ERROR-DETECTED PART
 Repair or replace error-detected parts.
 Reconnect part or connector after repairing or replacing.
 When DTC is detected, erase self-diagnostic result for “ABS”.
>> GO TO 7.
6.IDENTIFY ERROR-DETECTED S YSTEM BY SYMPTOM DIAGNOSIS
Estimate error-detected system based on symptom diagnosis and perform inspection.
Can the error-detected system be identified?
Revision: 2010 May2011 QX56