2007 INFINITI QX56 clutch

TF-18
< SERVICE INFORMATION >
ALL-MODE 4WD SYSTEM
LINE PRESSURE SWITCH
• With the transfer system design, control of the oil pressure provides the transmission of drive torque to the
front wheels. The main pressure to control the oil pressure is referred to as the line pressure.
• The line pressure switch determines whether or not adequate line pressure has built up under different oper-
ating conditions.
• The line pressure switch turns ON when line pressure is produced.
• The line pressure switch senses line pressure abnormalities and turns the 4WD warning lamp ON.
CLUTCH PRESSURE SWITCH
• The clutch pressure switch determines whether or not adequate clutch pressure has built up under different
operating conditions.
• The clutch pressure switch turns ON when clutch pressure is produced.
• The clutch pressure switch senses clutch pressure abnormalities and turns the 4WD warning lamp ON.
TRANSFER FLUID TEMPERATURE SENSOR
The transfer temperature sensor detects the transfer fluid temperature and sends a signal to the transfer con-
trol unit.
TRANSFER CONTROL UNIT
• Transfer control unit controls transfer control device by input signals of each sensor and each switch.
• Self-diagnosis can be done.
TRANSFER CONTROL DEVICE
The transfer control device changes the state of transfer assembly between 2WD, AUTO, 4H⇔4LO with the
2WD, AUTO, 4H and 4LO signals of 4WD shift switch.
NOTE:
• To shift between 4H⇔4LO, stop the vehicle, depress the brake pedal and shift the transmission selector to
the "N" position. Depress and turn the 4WD shift switch. The shift switch will not shift to the desired mode if
the transmission is not in "N" or the vehicle is moving. The 4LO indicator lamp will be lit when the 4LO is
engaged.
• Actuator motor and actuator position switch are integrated.
4WD SHIFT SWITCH AND INDICATOR LAMP
4WD Shift Switch
The 4WD shift switch allows selection from 2WD, AUTO, 4H or 4LO.
4WD Shift Indicator Lamp
• Displays driving conditions selected by 4WD shift switch with 2WD, AUTO and 4H indicators while engine is
running. (When 4WD warning lamp is turned on, all 4WD shift indicator lamps are turned off.)
• Turns ON for approximately 1 second when ignition switch is turned ON, for purpose of lamp check.
4LO Indicator Lamp
• Displays 4LO condition while engine is running. 4LO indicator lamp flashes if transfer gear does not shift
completely under 2WD, AUTO, 4H⇔4LO. (When 4WD warning lamp is turned on, 4LO indicator lamp is
turned off.)
• Turns ON for approximately 1 second when ignition switch is turned ON, for purpose of lamp check.
4WD WARNING LAMP
Turns ON or FLASH when there is a malfunction in 4WD system.
Also turns ON when ignition switch is turned ON, for purpose of lamp check. Turns OFF for approximately 1
second after the engine starts if system is normal.
4WD Warning Lamp Indication
Condition Content 4WD warning lamp
During self-diagnosis Indicates the malfunction position by number of flickers. Flickers at malfunction mode.
Lamp check*Checks the lamp by turning ON during engine starting. After
engine starts, it turns OFF if there are no malfunctions.ON
Malfunction in 4WD system*Turns ON to indicate malfunction. When ignition switch is
turned to “OFF” or the malfunction is corrected, it turns OFF.ON
When vehicle is driven with different
diameters of front and rear tiresFlickers once every 2 seconds.
Turns OFF when ignition switch is “OFF”.Flickers once every 2 sec-
onds.

ALL-MODE 4WD SYSTEM
TF-19
< SERVICE INFORMATION >
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*: When 4WD warning lamp is ON, all the 4WD shift indicator lamps turn OFF.
ATP WARNING LAMP
Even if A/T selector lever is in “P” position, vehicle may move because A/T parking mechanism does not oper-
ate when transfer is under neutral condition. ATP warning lamp is turned on so as to indicate this condition to
the driver.
SchematicINFOID:0000000003532518
COMPONENTS FUNCTION
High fluid temperature in transfer unitWhen fluid temperature is high or fluid temperature sensor cir-
cuit is shorted, it flickers twice every second.
It turns OFF when fluid temperature becomes normal.Flickers twice a second.
Other than above (System is normal.) Lamp is OFF. OFFCondition Content 4WD warning lamp
WDIA0164E
Component parts Function
Transfer control unit Controls transfer control device and control valves.
Transfer control device Actuator motor and actuator position switch are integrated so as to switch driving types.
2-4WD shift solenoid valve Controls oil pressure and allows selection between 2WD and 4WD.
Clutch pressure solenoid valve Controls oil pressure and distributes torque (front and rear).
Line pressure switch Detects line pressure.
Clutch pressure switch Detects clutch pressure.
Transfer fluid temperature sen-
sorDetects transfer fluid temperature.
Wait detection switch Detects whether or not 4WD lock gear is locked.
Neutral-4LO switch Detects that transfer is under neutral-4LO condition (or shifting through neutral).
ATP switch Detects that transfer is under neutral condition.
4WD shift switch Allows selection from 2WD, AUTO, 4H or 4LO.
4WD warning lamp• Illuminates if malfunction is detected in electrical system of 4WD system.
• There is 1 blink every 2 seconds if rotation difference of front wheels and rear wheels is large.
• There is 2 blinks every 1 second if high transfer fluid temperature is detected.
AT P w a r n i n g l a m pIndicates that A/T parking mechanism does not operate when A/T selector lever is in “P” position and
transfer is under neutral condition.
4WD shift indicator lamp Displays driving condition selected by 4WD shift switch.
4LO indicator lamp Displays 4LO condition.

TF-34
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Trouble Diagnosis Chart by Symptom
INFOID:0000000003532525
If 4WD warning lamp turns ON, perform self-diagnosis. Refer to TF-48, "Self-Diagnosis Procedure" .
NOTE:
• Light tight-corner braking symptom may occur depending on driving conditions in AUTO mode. This is not a
malfunction.
Symptom Condition Check item Reference page
4WD shift indicator lamp and 4LO indicator
lamp do not turn ON
(4WD shift indicator lamp and 4LO indicator
lamp check)Ignition switch: ONPower supply and ground for transfer
control unit
TF-102
Transfer shut off relay
Combination meter
4WD warning lamp does not turn ON
(4WD warning lamp check)Ignition switch: ONPower supply and ground for transfer
control unit
TF-104
Transfer shut off relay
Combination meter
4WD shift indicator lamp or 4LO indicator
lamp does not changeEngine running4WD shift switch
TF-107
Wait detection switch
Neutral-4LO switch
ATP switch
2-4WD solenoid
Transfer control device
Actuator motor
Actuator position switch
Transfer inner parts
ATP warning lamp turns ON Engine runningCAN communication line
TF-109
4WD shift switch
PNP switch signal
ATP switch
Combination meter
Transfer inner parts
4LO indicator lamp repeats flashing Engine runningWait detection switch
TF-110
Neutral-4LO switch
Transfer inner parts
4WD warning lamp flashes rapidly (2 times/
second)While drivingTransfer fluid temperature
TF-111
Tire size is different between front and
rear of vehicle
4WD warning lamp flashes slowly
(1 time/2 seconds)While drivingTire size is different between front and
rear of vehicle.
TF-112
Transfer fluid temperature
Clutch pressure switch
Heavy tight-corner braking symptom occurs
(See NOTE.)• While driving
•AUTO mode
• Steering wheel is
turned fully to either
sideCAN communication line
TF-113
4WD shift switch
Accelerator pedal position signal
Clutch pressure solenoid
Transfer inner parts
4WD system does not operate While driving4WD shift switch
TF-114
Clutch pressure switch
Transfer inner parts

TF-36
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
ATP SWITCH [ON/OFF] Condition of ATP switch• Vehicle stopped
• Engine running
• A/T selector lever “N”
• Brake pedal depressed4WD shift switch
: 4H to 4LO or 4LO to 4H
(While actuator motor is
operating.) ON
Except the above OFF
WAIT DETCT SW [ON/
OFF]Condition of wait detec-
tion switch• Vehicle stopped
• Engine running
• A/T selector lever “N” posi-
tion
• Brake pedal depressed4WD shift switch: 2WD,
AUTO or 4HOFF
4WD shift switch: 4H to
4LO (While actuator mo-
tor is operating.)OFF → ON
4WD shift switch: 4LO to
4H (While actuator motor
is operating.)ON → OFF
4WD shift switch: 4LO ON
LINE PRES SW [ON/
OFF]Condition of line pres-
sure switch• A/T selector lever “D” position
• 4WD shift switch: 2WD, AUTO or 4HON
• Except the above
• The vehicle has been left at
room temperature for 5
minutes and more with ig-
nition switch in “OFF” posi-
tion.• Ignition switch: ON
• A/T selector lever: “P”
or "N" position
• 4WD shift switch: other
than AUTOOFF
CL PRES SW [ON / OFF]Condition of clutch pres-
sure switch• Vehicle stopped
• Engine running
• A/T selector lever “D” position
• 4WD shift switch: AUTO or 4H (“Wait” function is not op-
erating.)ON
• Vehicle stopped
• Engine running
• 4WD shift switch: 2WD (“Wait” function is not operat-
ing.)OFF
N POSI SW AT [ON/
OFF]Input condition from A/T
PNP switch• Vehicle stopped
• Engine running
• Brake pedal depressedA/T selector lever posi-
tion: NON
Except the above OFF
R POSI SW AT [ON/
OFF]Input condition from A/T
PNP switch• Vehicle stopped
• Engine running
• Brake pedal depressedA/T selector lever posi-
tion: RON
Except the above OFF
P POSI SW AT [ON/OFF]Input condition from A/T
PNP switch• Vehicle stopped
• Engine running
• Brake pedal depressedA/T selector lever posi-
tion: PON
Except the above OFF
ABS OPER SW [ON/
OFF]Condition of ABS operat-
ingABS is operating. ON
ABS is not operating. OFF
VDC OPER SW [ON/
OFF]Condition of VDC operat-
ingVDC is operating. ON
VDC is not operating. OFF
TCS OPER SW [ON/
OFF]Condition of TCS operat-
ingTCS is operating. ON
TCS is not operating. OFF
THROTTLE POSI [0.0/8]Condition of throttle
openingWhen depressing accelerator pedal
(Value rises gradually in response to throttle position.)0.0/8 - 8.0/8
4WD MODE [AUTO/
LOCK/2WD/4L]Control status of 4WD
(Output condition of 4WD
shift indicator lamp and
4LO indicator lamp)• Vehicle stopped
• Engine running
• A/T selector lever “N” posi-
tion
• Brake pedal depressed4WD shift switch: 2WD 2WD
4WD shift switch: AUTO AUTO
4WD shift switch: 4H LOCK
4WD shift switch: 4LO 4L Monitored item [Unit] Content Condition Display value

TROUBLE DIAGNOSIS
TF-37
< SERVICE INFORMATION >
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VHCL/S COMP [km/h] or
[mph]Vehicle speedVehicle stopped 0 km/h (0 MPH)
Vehicle running
CAUTION:
Check air pressure of tire under standard condition.Approximately
equal to the indica-
tion on speedome-
ter (Inside of
±10%)
COMP CL TORQ [kgm]Condition of control
torque• Vehicle stopped
• Engine running
• A/T selector lever “N” posi-
tion
• Brake pedal depressed4WD shift switch: 2WD 0 kg-m
4WD shift switch: AUTO39 - 1,353 N·m
(4 - 138 kg-m, 29 -
998 ft-lb)
4WD shift switch: 4H or
4LO1,353 N·m
(138 kg-m, 998 ft-
lb)
DUTY SOLENOID [%]Condition of clutch pres-
sure solenoid• Vehicle stopped
• Engine running
• A/T selector lever “N” posi-
tion
• Brake pedal depressed4WD shift switch: 2WD 4%
4WD shift switch: AUTO 96 - 4%
4WD shift switch: 4H or
4LO4%
2-4WD SOL [ON/OFF]Condition of 2-4WD shift
solenoid valve• Vehicle stopped
• Engine running
• A/T selector lever “N” posi-
tion
• Brake pedal depressed4WD shift switch: 2WD OFF
4WD shift switch: AUTO
ON 4WD shift switch: 4H
4WD shift switch: 4LO
4WD shift switch: AUTO
(“Wait” function is operat-
ing.)OFF
4WD shift switch: 4H
(“Wait” function is operat-
ing.)OFF
2-4WD SOL MON [ON/
OFF]Check signal for transfer
control unit signal output• Vehicle stopped
• Engine running
• A/T selector lever “N” posi-
tion
• Brake pedal depressed4WD shift switch: 2WD OFF
4WD shift switch: AUTO
ON 4WD shift switch: 4H
4WD shift switch: 4LO
4WD shift switch: AUTO
(“Wait” function is operat-
ing.)OFF
4WD shift switch: 4H
(“Wait” function is operat-
ing.)OFF
MOTOR RELAY [ON/
OFF]Condition of transfer mo-
tor relay• Accelerator pedal de-
pressed
• Vehicle stopped
• Engine running
• Brake pedal depressed4WD shift switch: 2WD OFF
4WD shift switch: AUTO
or 4LO (A/T selector lever
“P” or “N” position)OFF
("ON" for approx. 2
sec. after shifting
to “P” and “N”.)
4WD shift switch: AUTO
or 4LO (Except for A/T se-
lector lever “P” or “N” po-
sition)ON
4WD shift switch: 4H (A/T
selector lever “P” posi-
tion)OFF
("ON" for approx. 2
sec. after shifting
to “P”.)
4WD shift switch: 4H (Ex-
cept for A/T selector lever
“P” position)ON Monitored item [Unit] Content Condition Display value

TF-40
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
10 L/W Transfer dropping resistor• Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de-
pressed4WD shift switch: AUTO 4 - 14V
4WD shift switch: 2WD, 4H or 4LO Less than 1V
11 L4WD shift indicator lamp
(Lock indicator lamp)Lock indicator lamp of 4WD shift indicator lamp: OFF Battery voltage
Lock indicator lamp of 4WD shift indicator lamp: ON 0V
12 W/G 4LO indicator lamp4LO indicator lamp: OFF Battery voltage
4LO indicator lamp: ON 0V
13 G/B Transfer shift low relay• Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de-
pressed4WD shift switch: 4LO to 4H (“Wait” func-
tion is operating.)Battery voltage
Except the above 0V
14 LG Transfer motor relay• Accelerator pedal
depressed
• Vehicle stopped
• Engine running
• Brake pedal de-
pressed4WD shift switch: 2WD Battery voltage
4WD shift switch: AUTO or 4LO (A/T selec-
tor lever “P” or “N” position)Battery voltage
(0V for approx.
2 sec. after
shifting to “P”
and “N”.)
4WD shift switch: AUTO or 4LO (Except for
A/T selector lever “P” or “N” position)0V
4WD shift switch: 4H (A/T selector lever
“P” position)Battery voltage
(0V for approx.
2 sec. after
shifting to “P”.)
4WD shift switch: 4H (Except for A/T selec-
tor lever “P” position)0V
15 L/B ATP warning lampATP indicator lamp: ON 0V
ATP indicatorlamp: OFF Battery voltage
16 Y/R Power supplyIgnition switch: ON Battery voltage
Ignition switch: OFF 0V
18 O4WD shift switch
(4H)Ignition switch: ON4WD shift switch: 4H Battery voltage
4WD shift switch: 2WD, AUTO or 4LO 0V
19 LClutch pressure solenoid
valve• Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de-
pressed4WD shift switch: AUTO 1.5 - 3V
4WD shift switch: 2WD, 4H or 4LO Less than 1V
21 BR4WD shift indicator lamp
(AUTO indicator lamp)• AUTO indicator lamp of 4WD shift indicator lamp: OFF Battery voltage
AUTO indicator lamp of 4WD shift indicator lamp: ON 0V
22 Y/R Power supplyIgnition switch: ON Battery voltage
Ignition switch: OFF 0V
23 R4WD shift switch
(4LO)Ignition switch: ON4WD shift switch: 4LO Battery voltage
4WD shift switch: 2WD, AUTO or 4H 0V
24 LG/R4WD shift switch
(AUTO)Ignition switch: ON4WD shift switch: AUTO Battery voltage
4WD shift switch: 2WD, 4H or 4LO 0V Te r m i n a lWire
colorItem Condition Data (Approx.)

TROUBLE DIAGNOSIS
TF-41
< SERVICE INFORMATION >
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25 V Neutral-4LO switch• Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de-
pressed4WD shift switch: 2WD, AUTO or 4H Battery voltage
4WD shift switch: 4H to 4LO (While actua-
tor motor is operating.)Battery voltage
→ 0V
4WD shift switch: 4LO to 4H (While actua-
tor motor is operating.)0V → Battery
voltage
4WD shift switch: 4LO 0V
27 W/LActuator position switch 2
(High)• Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de-
pressed4WD shift switch: 4H, AUTO or 2WD 0V
4WD shift switch: 4LO Battery voltage
28 B/G Sensor ground Always 0V
29 L/W Ignition switch monitorIgnition switch: ON Battery voltage
Ignition switch: OFF 0V
30 SB Shut off relayIgnition switch: ON 0V
Ignition switch: OFF Battery voltage
31 GTransfer fluid temperature
sensorIgnition switch: ONTransfer fluid temperature approx. 20°C
(68°F)1.1V
Transfer fluid temperature approx. 80°C
(176°F)0.3V
33 R/LTransfer shift high relay
monitor• Vehicle stopped
• Engine running
• A/T selector lever
“N” position
• Brake pedal de-
pressed4WD shift switch: 4H to 4LO (“Wait” func-
tion is operating.)Battery voltage
Except the above 0V
34 BR Clutch pressure switch• Vehicle stopped
• Engine running
• A/T selector lever
“D” position4WD shift switch: AUTO or 4H (“Wait” func-
tion is not operating.)0V
• Vehicle stopped
• Engine running4WD shift switch: 2WD (“Wait” function is
not operating.)Battery voltage
35BR/
WLine pressure switch• Ignition switch: ON
• A/T selector lever “D” position
• 4WD shift switch: AUTO0V
• After the vehicle
has been left at
room temperature
for 5 minutes and
more with ignition
switch in “OFF” po-
sition.• Ignition switch: ON
• A/T selector lever: “P” or "N" position
• 4WD shift switch: other than AUTOBattery voltage
40 L ATP switch• Vehicle stopped
• Engine running
• A/T selector lever
“N”
• Brake pedal de-
pressed4WD shift switch: 4H to 4LO or 4LO to 4H
(While actuator motor is operating.)0V
Except the above Battery voltage Te r m i n a lWire
colorItem Condition Data (Approx.)

TF-44
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
CAUTION:
• If “CAN COMM CIRCUIT [U1000]” is displayed with other DTCs, first perform the trouble diagnosis for CAN communication
line.
• If “VHCL SPEED SEN·AT [P1808]”, “ABS OP SIG [P1830]”, “VDC OP SIG [P1831]” or “TCS OP SIG [P1832]” is displayed, first
perform the trouble diagnosis for ABS system.
• If “VHCL SPEED SEN·AT [P1808]”, is displayed, first perform the trouble diagnosis for A/T system.
NOTE:
• If "SHIFT ACT POSI SW [P1818]" or “SHIFT ACT CIR [P1819]” is displayed, first erase self-diagnostic results. ("SHIFT ACT POSI SW
[P1818]" or “SHIFT ACT CIR [P1819]” may be displayed after installing transfer control unit or transfer assembly.)
• If “CL PRES SW [P1827]” or “LINE PRES SW [P1828]” is displayed only while driving in reverse, check the continuity of “R” position
on A/T PNP switch. When there is nothing wrong with the electrical system, check the hydraulic system.
How to Erase Self-diagnostic Results
1. Perform applicable inspection of malfunctioning item and then repair or replace.
SHIFT ACT CIR
[P1819]• Transfer control device actuator circuit is shorted or open. (Mal-
functions are detected when transfer shift relay circuit is open/
shorted or relay monitor circuit is open/shorted.)
• Malfunction occurs in transfer control device drive circuit.
• Malfunction is detected in transfer shut off relay.TF-72, "Transfer Control Device"
Malfunction is detected in transfer shut off relay.TF-51, "Power Supply Circuit for
Transfer Control Unit"
ENGINE SPEED SIG
[P1820]• Malfunction is detected in engine speed signal that is output from
ECM through CAN communication.
• Improper signal is input while driving.TF-76, "Engine Speed Signal
(ECM)"
DUTY SOLENOID
[P1822]• Proper voltage is not applied to clutch pressure solenoid valve
due to open or short circuit.TF-76, "Clutch Pressure Sole-
noid"
2-4WD SOLENOID
[P1823]• Proper voltage is not applied to 2-4WD solenoid valve due to open
or short circuit.TF-80, "2-4WD Solenoid"
MOTOR RELAY
[P1824]• Motor does not operate properly due to open or short circuit in
transfer motor or motor relay.TF-84, "Transfer Motor"
OIL TEMP SEN
[P1826]• Signal voltage from fluid temperature sensor is abnormally high
(Transfer fluid temperature is abnormally low) while driving.TF-90, "Transfer Fluid Tempera-
ture"
CLUTCH PRES SW
[P1827]• Improper signal from clutch pressure switch is input due to open or
short circuit.
• Malfunction occurs in clutch pressure switch or hydraulic circuit.TF-92, "Clutch Pressure Switch"
LINE PRES SW
[P1828]• Improper signal from line pressure switch is input due to open or
short circuit.
• Malfunction occurs in line pressure switch or hydraulic circuit.TF-94, "Line Pressure Switch"
THROTTLE POSI SEN
[P1829]• Malfunction is detected in accelerator pedal position signal that is
output from ECM through CAN communication.
• Signal voltage from accelerator pedal position sensor is abnormal-
ly high or low.TF-97, "Throttle Position Signal
(ECM)"
ABS OP SIG
[P1830]• Malfunction is detected in ABS operation signal that is output from
ABS actuator and electric unit (control unit) through CAN commu-
nication.TF-97, "ABS Operation Signal
(ABS)"
VDC OP SIG
[P1831]• Malfunction is detected in VDC operation signal that is output from
ABS actuator and electric unit (control unit) through CAN commu-
nication.TF-98, "VDC Operation Signal
(ABS)"
TCS OP SIG
[P1832]• Malfunction is detected in TCS operation signal that is output from
ABS through CAN communication.TF-98, "TCS Operation Signal
(ABS)"
CAN COMM CIRCUIT
[U1000]• Malfunction has been detected from CAN communication line.TF-99, "CAN Communication
Line"
NO DTC IS DETECTED.
FURTHER TESTING MAY
BE REQUIRED.• No NG item has been detected. — Items (CONSULT-II screen
terms)Diagnostic item is detected when... Check item