2006 INFINITI QX56 check engine

TRANSFER FLUIDTF-11
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Revision: November 2009 2006 QX56
TRANSFER FLUIDPFP:31001
ReplacementEDS003B6
DRAINING
1. Stop the engine.
2. Remove the drain plug and gasket to drain the transfer fluid as
shown.
3. Install the new gasket on the drain plug and install the drain plug in the transfer. Tighten the drain plug to specification.
CAUTION:
Do not reuse the gasket.
FILLING
1. Remove the filler plug and gasket.
2. Fill with new specified fluid until the fluid level reaches the spec-ified limit near the filler plug hole as shown.
CAUTION:
Carefully fill the transfer with fluid. Filling should take
approximately three minutes.
3. Leave the vehicle for three minutes and then check the fluid level again as shown.
4. Install the new gasket on the filler plug and install the filler plug in the transfer. Tighten the filler plug to specification.
CAUTION:
Do not reuse the gasket.
InspectionEDS003B7
FLUID LEAKAGE AND FLUID LEVEL
1. Check for any fluid leaks from the transfer assembly or around it and correct as necessary.
2. Remove the filler plug to check the fluid level at the filler plug
hole as shown.
CAUTION:
Do not start the engine while checking the fluid level.
3. Install the new gasket on the filler plug and install the filler plug in the transfer. Tighten the filler plug to specification.
CAUTION:
Do not reuse the gasket.Drain plug : Refer to
TF-146, "
COMPONENTS" .
SDIA3208E
Fluid capacity and grade : Refer to MA-11, "Fluids
and Lubricants" .
Filler plug : Refer to TF-146, "
COMPONENTS" .
SDIA3209E
Filler plug : Refer to TF-146, "COMPONENTS" .
SDIA3209E

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.

ALL-MODE 4WD SYSTEMTF-19
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Revision: November 2009 2006 QX56
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
*: 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.
System DiagramEDS002HB
Condition Content4WD 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 tires Flickers once every 2 seconds.
Turns OFF when ignition switch is
“OFF ”. Flickers once every 2 sec-
onds.
High fluid temperature in transfer unit When 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 nor-
mal.) Lamp is OFF.
OFF
WDIA0164E

TF-32
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
Inspections Before Trouble DiagnosisEDS002HH
TRANSFER FLUID CHECK
Check fluid for leaks and fluid level. Refer to TF-11, "Inspection" .
PREPARATION FOR ROAD TEST

The purpose of the test is to determine overall performance of
transfer and analyze causes of problems.

When a malfunction is found in any part of transfer, perform the
road test to locate the malfunction area and repair the malfunc-
tion parts.

The road test consists of the following three parts.
–Check before engine is started. Refer to TF-32, "CHECK
BEFORE ENGINE IS STARTED" .
–Check at idle. Refer to TF-32, "CHECK AT IDLE" .
–Cruise test. Refer to TF-33, "CRUISE TEST" .
CHECK BEFORE ENGINE IS STARTED
1. CHECK 4WD SHIFT INDICATOR LAMP
1. Park vehicle on flat surface.
2. Turn ignition switch to “OFF ” position.
3. Move A/T selector lever to “P ” position.
4. Set 4WD shift switch to “2WD” position.
5. Turn ignition switch to “ON ” position. (Do not start engine.)
Does 4WD shift indicator lamp turn ON for approximately 1 second?
YES >> GO TO 2.
NO >> Go to TF-117, "
4WD Shift Indicator Lamp and 4LO Indicator Lamp Do Not Turn ON" .
2. CHECK 4WD WARNING LAMP
1. Turn ignition switch to “OFF ” position.
2. Move A/T selector lever to “P ” position.
3. Set 4WD shift switch to “2WD” position.
4. Turn ignition switch to “ON ” position. (Do not start engine.)
Does 4WD warning lamp turn ON?
YES >> GO TO TF-32, "CHECK AT IDLE" .
NO >> GO TO TF-121, "
4WD Warning Lamp Does Not Turn ON" .
CHECK AT IDLE
1. CHECK 4WD SHIFT INDICATOR LAMP
1. Park vehicle on flat surface and engage the parking brake.
2. Turn ignition switch to “OFF ” position.
3. Move A/T selector lever to “P ” position.
4. Set 4WD shift switch to “2WD” position.
5. Start engine.
Does 4WD shift indicator lamp turn ON?
YES >> GO TO 3.
NO >> GO TO 2.
SMT089D

TROUBLE DIAGNOSISTF-33
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2. CHECK 4WD WARNING LAMP
Check 4WD warning lamp state?
Is 4WD warning lamp turned ON?
YES >> Perform the self-diagnosis. Refer to TF-50, "SELF-DIAGNOSTIC PROCEDURE (WITH CON-
SULT-II)" (with CONSULT-II) or TF-50, "SELF-DIAGNOSTIC PROCEDURE (WITHOUT CON-
SULT-II)" (without CONSULT-II).
NO >> Go to TF-123, "
4WD Shift Indicator Lamp or 4LO Indicator Lamp Does Not Change" .
3. CHECK 4WD SHIFT INDICATOR AND 4LO INDICATOR OPERATION
1. Brake pedal depressed.
2. Move A/T selector lever to “N” position.
3. Set 4WD shift switch to “2WD”, “AUTO ”, “4H ”, “4LO ”, “4H ”,
“AUTO ” and “2WD” in order. (Stay at each switch position for at
least 1 second.)
Do 4WD shift indicator and 4LO indicator lamps change properly?
Does buzzer sound?
YES >> GO TO TF-33, "CRUISE TEST" .
NO >> GO TO TF-123, "
4WD Shift Indicator Lamp or 4LO Indi-
cator Lamp Does Not Change" .
CRUISE TEST
1. CHECK INPUT SIGNAL
1. Warm up engine to normal operating temperature.
2. Park vehicle on flat surface.
3. Move A/T selector lever to “P” position.
4. Set 4WD shift switch to “AUTO” position.
5. Start engine.
6. Drive vehicle for at least 30 seconds at a speed higher than 20 km/h (12 MPH).
Check 4WD warning lamp turned ON?
On steady>>Perform the self-diagnosis. Refer to TF-50, "SELF-DIAGNOSTIC PROCEDURE (WITH CON-
SULT-II)" (with CONSULT-II) or TF-50, "SELF-DIAGNOSTIC PROCEDURE (WITHOUT CON-
SULT-II)" (without CONSULT-II).
Flash rapidly>>GO TO TF-128, "
4WD Warning Lamp Flashes Rapidly" .
Flash slowly>>GO TO TF-129, "
4WD Warning Lamp Flashes Slowly" .
NO >> GO TO 2.
WDIA0136E

TF-34
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
2. CHECK TIGHT CORNER BRAKING SYMPTOM (1)
1. Set 4WD shift switch to “AUTO” position.
2. Drive vehicle at speed lower than 20 km/h (12 MPH) with steering wheel fully turned.
Does tight corner braking symptom occur?
YES >> GO TO TF-130, "Heavy Tight-corner Braking Symptom Occurs" .
NO >> GO TO 3.
3. CHECK TIGHT CORNER BRAKING SYMPTOM (2)
1. Set 4WD shift switch to “4HI” position.
2. Drive vehicle at speed lower than 20 km/h (12 MPH) with steering wheel fully turned.
Does tight corner braking symptom occur?
YES >> Inspection End.
NO >> GO TO TF-131, "
4WD System Does Not Operate" .
Trouble Diagnosis Chart for SymptomsEDS002HI
If 4WD warning lamp turns ON, perform self-diagnosis. Refer to TF-50, "Self-diagnostic Procedure" .
Symptom ConditionCheck itemReference 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-117
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-121
Transfer shut off relay
Combination meter
4WD shift indicator lamp or 4LO indicator
lamp does not change Engine running4WD shift switch
TF-123
Wait detection switch
Neutral-4LO switch
AT P s w i t c h
2-4WD solenoid
Transfer control device
Actuator motor
Actuator position switch
Transfer inner parts
ATP warning lamp turns ON Engine running CAN communication line
TF-125
4WD shift switch
PNP switch signal
AT P s w i t c h
Combination meter
Transfer inner parts
4LO indicator lamp repeats flashing Engine running Wait 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

TROUBLE DIAGNOSISTF-35
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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.
Transfer Control Unit Input/Output Signal Reference ValuesEDS002HJ
TRANSFER CONTROL UNIT INSPECTION TABLE
Specifications with CONSULT-II
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
side CAN communication line
TF-130
4WD shift switch
Accelerator pedal position signal
Clutch pressure solenoid
Transfer inner parts
4WD system does not operate While driving 4WD shift switch
TF-131
Clutch pressure switch
Transfer inner parts
Symptom
ConditionCheck itemReference page
Monitored item [Unit] Content ConditionDisplay value
VHCL/S SEN ·FR [km/h]
or [mph] Front wheel 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%)
VHCL/S SEN ·RR [km/h]
or [mph] Rear wheel 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%)
ENGINE SPEED [rpm] Engine speed Engine stopped
(Engine speed: Less than 400 rpm)
0 rpm
Engine running
(Engine speed: 400 rpm or more) Approximately
equal to the indi-
cation on tachom-
eter
THRTL POS SEN [V] Accelerator pedal posi-
tion (APP) sensor signal
voltage Accelerator pedal: Release
Approx. 0.5V
Accelerator pedal: Fully depressed Approx. 4.0V
FLUID TEMP SE [V] Transfer fluid tempera-
ture signal voltage Transfer fluid temperature approx. 20 - 80°C (68 - 176
°F) Approx. 1.1 - 0.3V
BATTERY VOLT [V] Power supply voltage for
transfer control unit
Ignition switch: ON
Battery voltage
2WD SWITCH [ON/OFF] Input condition from
4WD shift switch 4WD shift switch: 2WD
ON
4WD shift switch: AUTO, 4H or 4LO OFF
AUTO SWITCH [ON/
OFF] Input condition from
4WD shift switch 4WD shift switch: AUTO
ON
4WD shift switch: 2WD, 4H or 4LO OFF

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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