2005 INFINITI QX4 clutch

TF-12
ALL-MODE 4WD SYSTEM
Revision: October 20052005 QX56
ALL-MODE 4WD SYSTEMPFP:00000
Cross-section ViewEDS002H8
1. Center case 2. Front case 3. Internal gear
4. Planetary carrier assembly 5. Sun gear assembly 6. Main shaft
7. L-H sleeve 8. L-H fork 9. Shift rod
10. 2-4 sleeve 11. 2-4 fork 12. Drive chain
13. Front drive shaft 14. Control valve assembly 15. Transfer motor
16. Rear case 17. Clutch piston 18. Press flange
19. Multiple disc clutch 20. Clutch hub assembly 21. Clutch drum assembly
WDIA0202E

ALL-MODE 4WD SYSTEM
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Power TransferEDS0 02 H9
POWER TRANSFER DIAGRAM
1. Center case 2. Chain 3. Multiple disc clutch
4. Rear case 5. Mainshaft 6. Clutch hub assembly
7. Sub oil pump 8. Transfer motor 9. Control valve
10. Front drive shaft 11. Drain plug 12. 2-4 sleeve
13. Sun gear assembly 14. L-H sleeve 15. Planetary carrier assembly
16. Internal gear 17. Front case
LDIA0053E

ALL-MODE 4WD SYSTEM
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Revision: October 20052005 QX56
Ta b l e 1
Ta b l e 2
*: After 2.5 seconds have elapsed.

4WD shift switch, PNP switch, Neutral-4LO switch, vehicle speed sensor and throttle position sensor are
used in conjunction with the transfer motor.
WAIT DETECTION SWITCH

The wait detection switch operates when there is “circulating” torque produced in the propeller shaft
(L→H) or when there is a phase difference between 2-4 sleeve and clutch drum (H→L). After the release
of the “circulating” torque, the wait detection switch helps provide the 4WD lock gear (clutch drum) shifts.
A difference may occur between the operation of the 4WD shift switch and actual drive mode. At this
point, the wait detection switch senses an actual drive mode.

The wait detection switch operates as follows.
–4WD lock gear (clutch drum) locked: ON
–4WD lock gear (clutch drum) released: OFF

The wait detection switch senses an actual drive mode and the 4WD shift indicator lamp indicates the
vehicle drive mode.
NEUTRAL-4LO SWITCH
The neutral-4LO switch detects that transfer gear is in neutral or 4LO (or shifting from neutral to 4LO) condi-
tion by L-H shift fork position.
ATP SWITCH
ATP switch detects if transfer gear is in a neutral condition by L-H shift fork position.
NOTE:
Transfer gear may be in a neutral condition in 4H-4LO.
2-4WD SHIFT SOLENOID VALVE
The 2-4WD shift solenoid valve operates to apply oil pressure to the wet-multiplate clutch, depending on the
drive mode. The driving force is transmitted to the front wheels through the clutch so the vehicle is set in the
4WD mode. Setting the vehicle in the 2WD mode requires no pressure buildup. In other words, pressure force
applied to the wet-multiplate clutch becomes zero.
CLUTCH PRESSURE SOLENOID VALVE
The clutch pressure solenoid valve distributes torque (front and rear) in AUTO mode.
PNP switch “R” position VFF (Vehicle speed) A/T position Motor relay drive command
ON — R ON
OFF0Positions other than the “P” or
“N” positionsON
—“P” or “N” position (See Table
2.)—
0 < VFF ≤ 50 km/h (31 MPH) — ON
50 km/h (31 MPH) < VFF < 55
km/h (34 MPH)—HOLD
55 km/h (34 MPH) ≤ VFF — OFF
A/T position N-4L SW 4WD modeThrottle position
0 - 0.07/8 0.07/8 - 1/8 1/8 - MAX
NOFFLOCK (4H) ON ON ON
Positions other than
the LOCK position
(2WD or AUTO)OFF* HOLD ON
ON — OFF* HOLD ON
P — — OFF* HOLD ON

TF-18
ALL-MODE 4WD SYSTEM
Revision: October 20052005 QX56
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
operating 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 differ-
ent 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.

TF-20
ALL-MODE 4WD SYSTEM
Revision: October 20052005 QX56
COMPONENTS FUNCTION
CAN CommunicationEDS002HC
SYSTEM DESCRIPTION
Refer to LAN-5, "CAN COMMUNICATION" .
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.
ATP warning lampIndicates 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.
ABS actuator and electric unit
(control unit)Transmits vehicle speed signal via CAN communication to transfer control unit.
TCMTransmits the following signals via CAN communication to transfer control unit.

Output shaft revolution signal

A/T position indicator signal (PNP switch signal)
ECMTransmits the following signals via CAN communication to transfer control unit.

Engine speed signal

Accelerator pedal position signal

TROUBLE DIAGNOSIS
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NOTE:

Light tight-corner braking symptom may occur depending on driving conditions in AUTO mode. This is not
a malfunction.

Heavy tight-corner braking symptom occurs when vehicle is driven in the following conditions: 4WD shift
switch is "4H" or "4LO", steering wheel is turned fully to either side.
4WD shift indicator lamp or 4LO indicator
lamp does not changeEngine running4WD shift switch
TF-123
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-125
4WD shift switch
PNP switch signal
ATP switch
Combination meter
Transfer inner parts
4LO indicator lamp repeats flashing Engine runningWait detection switch
TF-127
Neutral-4LO switch
Transfer inner parts
4WD warning lamp flashes rapidly (2 times/
second)While drivingTransfer fluid temperature
TF-128
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-129
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-130
4WD shift switch
Accelerator pedal position signal
Clutch pressure solenoid
Transfer inner parts
4WD system does not operate While driving4WD shift switch
TF-131
Clutch pressure switch
Transfer inner parts Symptom Condition Check item Reference page

TROUBLE DIAGNOSIS
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Revision: October 20052005 QX56
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
motor is operating.)OFF → ON
4WD shift switch: 4LO to
4H (While actuator motor
is operating.)OFF → ON
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
ignition switch in “OFF”
position.
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
operating.)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

TF-38
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
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 indi-
cation on speed-
ometer (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
motor relay

Accelerator pedal
depressed

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
selector lever “P” or “N”
position)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
(Except for A/T selector
lever “P” position)ON Monitored item [Unit] Content Condition Display value