2006 INFINITI QX56 torque

TF-18
ALL-MODE 4WD SYSTEM
Revision: November 20092006 QX56
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.
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: November 20092006 QX56
COMPONENTS FUNCTION
CAN CommunicationEDS002HC
SYSTEM DESCRIPTION
Refer to LAN-26, "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-
sor Detects 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 lamp Indicates 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.
TCM Transmits the following signals via CAN communication to transfer control unit.

Output shaft revolution signal

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

Engine speed signal

Accelerator pedal position signal

TROUBLE DIAGNOSISTF-37
CE F
G H
I
J
K L
M A
B
TF
Revision: November 2009 2006 QX56
P POSI SW AT [ON/
OFF]Input condition from A/T
PNP switch
Vehicle stopped

Engine running

Brake pedal depressed A/T selector lever posi-
tion: P
ON
Except the above OFF
ABS OPER SW [ON/
OFF] Condition of ABS operat-
ing ABS is operating.
ON
ABS is not operating. OFF
VDC OPER SW [ON/
OFF] Condition of VDC operat-
ing VDC is operating.
ON
VDC is not operating. OFF
TCS OPER SW [ON/
OFF] Condition of TCS operat-
ing TCS is operating.
ON
TCS is not operating. OFF
THROTTLE POSI [0.0/8] Condition of throttle
opening When 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 depressed 4WD shift switch: 2WD
2WD
4WD shift switch: AUTO AUTO
4WD shift switch: 4H LOCK
4WD shift switch: 4LO 4L
VHCL/S COMP [km/h] or
[mph] Vehicle speed Vehicle 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 depressed 4WD shift switch: 2WD 0 kg-m
4WD shift switch: AUTO
39 - 1,353 N
·m
(4 - 138 kg-m, 29 - 998 ft-lb)
4WD shift switch: 4H or
4LO 1,353 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 depressed 4WD shift switch: 2WD
4%
4WD shift switch: AUTO 96 - 4%
4WD shift switch: 4H or
4LO 4%
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 depressed 4WD 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
Monitored item [Unit]
Content ConditionDisplay value

TF-48
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
P POSI SW AT [ON/OFF]ז ד
P ” position signal of A/T PNP switch status is
displayed.
Signal input with CAN communication line.
ABS OPER SW [ON/OFF] ×– ×ABS operation signal status is displayed.
Signal input with CAN communication line.
VDC OPER SW [ON/OFF] ×– ×VDC operation signal status is displayed.
Signal input with CAN communication line.
TCS OPER SW [ON/OFF] ×– ×TCS operation signal status is displayed.
Signal input with CAN communication line.
THROTTLE POSI [0.0/8] – ×× Thottle position status is displayed.
Signal input with CAN communication line.
4WD MODE [AUTO/LOCK/2WD/4L] –×× Control status of 4WD recognized by transfer
control unit. (AUTO, 4H, 2WD or 4LO)
VHCL/S COMP [km/h] or [mph] – ×× Vehicle speed recognized by transfer control
unit.
COMP CL TORQ [kgm] – ×× Calculated torque recognized by transfer
control unit.
DUTY SOLENOID [%] – ×× Control value of clutch pressure solenoid.
2-4WD SOL [ON/OFF] –×× Output condition to 2-4WD solenoid.
2-4WD SOL MON [ON/OFF] – – ×Check signal for transfer control unit signal
output.
MOTOR RELAY [ON/OFF] – ×× Transfer motor relay signal status is dis-
played.
MOTOR RELAY MON [ON/OFF] – – ×Check signal for transfer control unit signal
output.
4WD FAIL LAMP [ON/OFF] – ×× Control status of 4WD warning lamp is dis-
played.
2WD IND [ON/OFF] ––×Control status of 4WD shift indicator lamp
(2WD indicator lamp) is displayed.
AUTO IND [ON/OFF] ––×Control status of 4WD shift indicator lamp
(2WD and AUTO indicator lamp) is displayed.
LOCK IND [ON/OFF] ––×Control status of 4WD shift indicator lamp
(2WD, AUTO and Lock indicator) is dis-
played.
4L IND [ON/OFF] ––×Control status of 4LO indicator lamp is dis-
played.
ATP IND [ON/OFF] ––×Control status of ATP warning lamp is dis-
played.
SHIFT POS SW1 [ON/OFF] ×– ×Actuator position switch 1 (Low) signal status
is displayed.
SHIFT POS SW2 [ON/OFF] ×– ×Actuator position switch 2 (high) signal status
is displayed.
SHIFT ACT1 [ON/OFF] –×× Output condition to actuator motor (clock-
wise)
SHIFT AC MON1 [ON/OFF] ×– ×Check signal for transfer control unit signal
output
SHIFT ACT2 [ON/OFF] –×× Output condition to actuator motor (counter-
clockwise)
SHIFT AC MON2 [ON/OFF] ×– ×Check signal for transfer control unit signal
output
Monitored item (Unit)
Monitor item selection
Remarks
ECU INPUT
SIGNALS MAIN
SIGNALS SELEC-
TION FROM MENU

TF-132
TRANSFER CONTROL UNIT
Revision: November 20092006 QX56
TRANSFER CONTROL UNITPFP:33084
Removal and InstallationEDS002IS
REMOVAL
1. Set transfer state as 2WD when 4WD shift switch is at 2WD, or as AUTO when 4WD shift switch is at
AUTO.
CAUTION:
When removing transfer control unit, transfer state must be at 2WD or AUTO.
2. Turn the ignition switch OFF and disconnect negative battery terminal.
3. Remove the glove box assembly. Refer to IP-14, "
Lower Instrument Panel RH and Glove Box" .
4. Disconnect the two transfer control unit connectors.
5. Remove the transfer control unit bolts.
6. Remove the transfer control unit.
INSTALLATION
Installation is in the reverse order of removal.

When installing the transfer control unit, tighten bolts to the specified torque.
CAUTION:

Do not connect harness connector to transfer control unit when 4WD shift switch is at 4LO.

After the installation, check perform self-diagnosis. Refer to TF-50, "Self-diagnostic Procedure" . If NG,
adjust position between transfer assembly and transfer control unit. Refer to TF-4, "
Precautions for Trans-
fer Assembly and Transfer Control Unit Replacement" .
BDIA0014E
Transfer control unit bolts : 5.1 N·m (0.52 kg-m, 45 in-lb)

TF-134
FRONT OIL SEAL
Revision: November 20092006 QX56
INSTALLATION
1. Install the new oil seal until it is flush with the end face of the
front case using Tool.
CAUTION:

Do not reuse oil seal.

Apply petroleum jelly to oil seal.
2. Align the matching mark of the front drive shaft with the match- ing mark of the companion flange, then install the companion
flange.
3. Install the new self-lock nut. Tighten to the specified torque using Tool. Refer to TF-146, "
COMPONENTS" .
CAUTION:
Do not reuse self-lock nut.
4. Install the front propeller shaft. Refer to PR-5, "
INSTALLATION"
.
5. Refill the transfer with fluid and check fluid level. Refer to TF-11,
"TRANSFER FLUID" .
6. Check the transfer for fluid leakage. Refer to TF-11, "
FLUID
LEAKAGE AND FLUID LEVEL" .
Tool number : KV38100500 ( — )
SDIA2662E
SDIA2658E
Tool number : KV40104000 ( — )
LDIA0147E

TF-142
TRANSFER MOTOR
Revision: November 20092006 QX56
TRANSFER MOTORPFP:00000
Removal and InstallationEDS003BD
REMOVAL
1. Disconnect the transfer motor connector.
2. Remove the air breather hose from the transfer motor. Refer to
TF-139, "
Removal and Installation" .
3. Remove the transfer motor bolts.
4. Remove the transfer motor.
INSTALLATION
1. Apply ATF to the new O-ring and install it to the transfer motor.
CAUTION:
Do not reuse O-rings.
2. Fit the double-flat end of the transfer motor shaft into the slot of the sub-oil pump assembly. Then tighten to the specified torque.
Refer to TF-146, "
COMPONENTS" .
CAUTION:
Be sure to install connector bracket.
3. Install the air breather hose to the transfer motor. Refer to TF-
139, "Removal and Installation" .
4. Connect the transfer motor connector.
5. Check the transfer fluid. Refer to TF-11, "
FILLING" .
6. Start the engine for one minute. Then stop the engine and recheck the transfer fluid. Refer to TF-11,
"FLUID LEAKAGE AND FLUID LEVEL" .
SDIA2133E
SDIA2787E

TF-144
TRANSFER OIL FILTER
Revision: November 20092006 QX56
3. Apply ATF to the two new O-rings (1), and install them on the oil
filter (2).
CAUTION:
Do not reuse O-rings.
4. Install the oil filter to the transfer assembly. Tighten the bolts to the specified torque. Refer to TF-146, "
COMPONENTS" .
CAUTION:

Do not damage oil filter.

Attach oil filter and tighten bolts evenly.
5. Check the transfer fluid. Refer to TF-11, "
TRANSFER FLUID" .
6. Start the engine and let it run for one minute. Then stop the engine and recheck the transfer fluid. Refer to TF-11, "
TRANS-
FER FLUID" .
WDIA0285E
SDIA2136E