2006 INFINITI QX56 warning

TF-4
PRECAUTIONS
Revision: November 20092006 QX56
PRECAUTIONSPFP:00001
Precautions for Supplemental Restraint System (SRS) “AIR BAG” and “SEAT
BELT PRE-TENSIONER”
EDS002H3
The Supplemental Restraint System such as “AIR BAG” and “SEAT BELT PRE-TENSIONER ”, used along
with a front seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain
types of collision. This system includes seat belt switch inputs and dual stage front air bag modules. The SRS
system uses the seat belt switches to determine the front air bag deployment, and may only deploy one front
air bag, depending on the severity of a collision and whether the front occupants are belted or unbelted.
Information necessary to service the system safely is included in the SRS and SB section of this Service Man-
ual.
WARNING:

To avoid rendering the SRS inoperative, which could increase the risk of personal injury or death
in the event of a collision which would result in air bag inflation, all maintenance must be per-
formed by an authorized NISSAN/INFINITI dealer.

Improper maintenance, including incorrect removal and installation of the SRS, can lead to per-
sonal injury caused by unintentional activation of the system. For removal of Spiral Cable and Air
Bag Module, see the SRS section.

Do not use electrical test equipment on any circuit related to the SRS unless instructed to in this
Service Manual. SRS wiring harnesses can be identified by yellow and/or orange harnesses or
harness connectors.
Precautions for Transfer Assembly and Transfer Control Unit ReplacementEDS002H4
When replacing transfer assembly or transfer control unit, check the 4WD shift indicator lamp as follows.
1. Turn ignition switch “ON ”.
2. Check 4WD shift indicator lamp is turned ON for approx. 1 second.

If OK, the position between transfer assembly and transfer control unit is correct.

If NG, the position is different between transfer assembly and transfer control unit.
Adjust the position between transfer assembly and transfer control unit. Refer to TF-4, "
METHOD FOR
POSITION ADJUSTMENT" .
METHOD FOR POSITION ADJUSTMENT
1. Start engine. Run the engine for at least 10 seconds.
2. Stop vehicle and move A/T selector lever to “N” position with brake pedal depressed. Stay in "N" for at
least 2 seconds.
3. Turn 4WD shift switch to “2WD ” position. Stay in "2WD" for at least 2 seconds.
4. Turn ignition switch “ OFF”.
5. Start engine.
6. Erase self-diagnosis. Refer to TF-47, "
How to Erase Self-diagnostic Results" (with CONSULT-II) or TF-
53, "ERASE SELF-DIAGNOSIS" (without CONSULT-II).
7. Check 4WD shift indicator lamp. Refer to TF-32, "
CHECK BEFORE ENGINE IS STARTED" .
If 4WD shift indicator lamp does not indicate "2WD", install new transfer control unit and retry the above
check.
PrecautionsEDS002H5

Before connecting or disconnecting the transfer control
unit harness connector, turn ignition switch “OFF” and dis-
connect battery ground cable. Failure to do so may damage
the transfer control unit. Battery voltage is applied to trans-
fer control unit even if ignition switch is turned “OFF”.
SEF289H

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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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-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

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