2006 INFINITI QX56 sensor

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

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Revision: November 2009 2006 QX56
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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Revision: November 2009 2006 QX56
Specifications Between Transfer Control Unit Terminals
TRANSFER CONTROL UNIT TERMINAL CONNECTOR LAYOUT
ATP IND [ON/OFF]Condition of ATP indica-
tor lamp ATP indicator lamp: ON
ON
ATP indicator lamp: OFF OFF
SHIFT POS SW1 [ON/
OFF] Condition of actuator
position switch 1
(Low)

Vehicle stopped

Engine running

A/T selector lever “
N” posi-
tion

Brake pedal depressed 4WD shift switch: 4LO
ON
4WD shift switch: 2WD,
AUTO or 4H OFF
SHIFT POS SW2 [ON/
OFF] Condition of actuator
position switch 2
(High)

Vehicle stopped

Engine running

A/T selector lever “
N” posi-
tion

Brake pedal depressed 4WD shift switch: 4H,
AUTO or 2WD
ON
4WD shift switch: 4LO OFF
SHIFT ACT1 [ON/OFF] Output condition to actu-
ator motor (High)

Vehicle stopped

Engine running

A/T selector lever “
N” posi-
tion

Brake pedal depressed 4WD shift switch: 4H to
4LO (
“Wait ” function is
operating.) ON
Except the above OFF
SHIFT AC MON1 [ON/
OFF] Check signal for transfer
control unit signal output

Vehicle stopped

Engine running

A/T selector lever “
N” posi-
tion

Brake pedal depressed 4WD shift switch: 4H to
4LO (
“Wait ” function is
operating.) ON
Except the above OFF
SHIFT ACT2 [ON/OFF] Output condition to actu-
ator motor (Low)

Vehicle stopped

Engine running

A/T selector lever “
N” posi-
tion

Brake pedal depressed 4WD shift switch: 4LO to
4H (
“Wait ” function is
operating.) ON
Except the above OFF
SHIFT AC MON2 [ON/
OFF] Check signal for transfer
control unit signal output

Vehicle stopped

Engine running

A/T selector lever “
N” posi-
tion

Brake pedal depressed 4WD shift switch: 4LO to
4H (
“Wait ” function is
operating.) ON
Except the above OFF
T/F F SPEED [km/h] or
[mph] Displayed, but do not use.
A/T R SPEED [km/h] or
[mph] Condition of vehicle
speed sensor A/T (Revo-
lution sensor)
During driving Approximately
matches the out-
put shaft speed.
AT GEAR POSI [1/2/3/4/
5] Condition of A/T selec-
tor lever position
Displays actual A/T gear position.
1/2/3/4/5
Monitored item [Unit]
Content ConditionDisplay value
WDIA0204E

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Revision: November 2009 2006 QX56
14 LG Transfer motor relay

Accelerator pedal
depressed

Vehicle stopped

Engine running

Brake pedal
depressed4WD shift switch: 2WD Battery voltage
4WD shift switch: AUTO or 4LO (A/T
selector 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
selector lever “P ” position) 0V
15 L/B ATP warning lamp ATP indicator lamp: ON
0V
ATP indicatorlamp: OFF Battery voltage
16 Y/R Power supply Ignition switch: ON
Battery voltage
Ignition switch: OFF 0V
18 O 4WD shift switch
(4H)
Ignition switch: ON4WD shift switch: 4H
Battery voltage
4WD shift switch: 2WD, AUTO or 4LO 0V
19 L Clutch pressure solenoid
valve

Vehicle stopped

Engine running

A/T selector lever
“
N ” position

Brake pedal
depressed 4WD shift switch: AUTO
1.5 - 3V
4WD shift switch: 2WD, 4H or 4LO Less than 1V
21 BR 4WD 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 supply Ignition switch: ON
Battery voltage
Ignition switch: OFF 0V
23 R 4WD shift switch
(4LO) Ignition switch: ON4WD shift switch: 4LO
Battery voltage
4WD shift switch: 2WD, AUTO or 4H 0V
24 LG/R 4WD shift switch
(AUTO) Ignition switch: ON4WD shift switch: AUTO
Battery voltage
4WD shift switch: 2WD, 4H or 4LO 0V
25 V Neutral-4LO switch

Vehicle stopped

Engine running

A/T selector lever
“ N ” position

Brake pedal
depressed 4WD shift switch: 2WD, AUTO or 4H Battery voltage
4WD shift switch: 4H to 4LO (While actua-
tor motor is operating.)
Battery volt-
age
→ 0V
4WD shift switch: 4LO to 4H (While actua-
tor motor is operating.) 0V
→ Battery
voltage
4WD shift switch: 4LO 0V
27 W/L Actuator position switch 2
(High)

Vehicle stopped

Engine running

A/T selector lever
“
N ” position

Brake pedal
depressed 4WD shift switch: 4H, AUTO or 2WD 0V
4WD shift switch: 4LO
Battery voltage
28 B/G Sensor ground Always0V
29 L/W Ignition switch monitor Ignition switch: ON
Battery voltage
Ignition switch: OFF 0V
Terminal
Wire
color Item
ConditionData (Approx.)

TF-42
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
30 SB Shut off relayIgnition switch: ON
0V
Ignition switch: OFF Battery voltage
31 G Transfer fluid temperature
sensor Ignition switch: ONTransfer fluid temperature approx. 20°C
(68
°F) 1.1V
Transfer fluid temperature approx. 80°C
(176 °F) 0.3V
33 R/L Transfer shift high relay
monitor

Vehicle stopped

Engine running

A/T selector lever
“
N ” position

Brake pedal
depressed 4WD 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 ” position 4WD shift switch: AUTO or 4H (
“Wait ”
function is not operating.) 0V

Vehicle stopped

Engine running4WD shift switch: 2WD (
“Wait ” function is
not operating.) Battery voltage
35 BR/
W Line pressure switch

Ignition switch: ON

A/T selector lever “
D” position

4WD shift switch: AUTO 0V

After 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 AUTO Battery voltage
40 L ATP switch

Vehicle stopped

Engine running

A/T selector lever
“ N ”

Brake pedal
depressed 4WD shift switch: 4H to 4LO or 4LO to 4H
(While actuator motor is operating.)
0V
Except the above Battery voltage
41 R Transfer motor relay moni-
tor

Accelerator pedal
depressed

Vehicle stopped

Engine running

Brake pedal
depressed 4WD shift switch: 2WD 0V
4WD shift switch: AUTO or 4LO (A/T
selector lever
“P ” or “ N” position) 0V
(Battery volt-
age 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) Battery voltage
4WD shift switch: 4H (A/T selector lever
“ P ” position) 0V
(Battery volt-
age for approx.
2 sec. after
shifting to
“P ”.)
4WD shift switch: 4H (Except for A/T
selector lever “P ” position) Battery voltage
Te r m i n a l
Wire
color Item
ConditionData (Approx.)

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SELF-DIAG RESULT MODE
Operation Procedure
1. Perform “CONSULT-II SETTING PROCEDURE ”. Refer to TF-44, "CONSULT-II SETTING PROCEDURE"
.
2. With engine at idle, touch “SELF-DIAG RESULTS”.
Display shows malfunction experienced since the last erasing
operation.
NOTE:

The details for “TIME” are as follow:
–“0”: Error currently detected with transfer control unit.
–Except for “0”: Error detected in the past and memorized
with transfer control unit.
Detects frequency of driving after DTC occurs (frequency
of turning ignition switch “ON/OFF”).
Display Item List
SDIA2687E
Items (CONSULT-II screen
terms) Diagnostic item is detected when...
Check item
CONTROL UNIT 1
[P1802]

Malfunction is detected in the memory (RAM) system of transfer
control unit. TF-57, "Transfer Control Unit"
CONTROL UNIT 2
[P1803]
Malfunction is detected in the memory (ROM) system of transfer
control unit.TF-57, "Transfer Control Unit"
CONTROL UNIT 3
[P1804]
Malfunction is detected in the memory (EEPROM) system of
transfer control unit.TF-57, "Transfer Control Unit"
VHCL SPEED SEN
·AT
[P1807]
Malfunction is detected in output shaft revolution signal that is
output from TCM through CAN communication.

Improper signal is input while driving. TF-58, "
Output Shaft Revolution
Signal (TCM)"
VHCL SPEED SEN
·ABS
[P1808]

Malfunction is detected in vehicle speed signal that is output from
ABS actuator and electric unit (control unit) through CAN commu-
nication.

Improper signal is input while driving. TF-58, "
Vehicle Speed Sensor
(ABS)"
CONTROL UNIT 4
[P1809]
AD converter system of transfer control unit is malfunctioning.
TF-57, "Transfer Control Unit"
4L POSI SW TF
[P1810]
Improper signal from neutral-4LO switch is input due to open or
short circuit.TF-59, "Neutral-4LO Switch"
BATTERY VOLTAGE
[P1811]
Power supply voltage for transfer control unit is abnormally low
while driving.TF-54, "Power Supply Circuit For
Transfer Control Unit"
4WD MODE SW
[P1813]
More than two switch inputs are simultaneously detected due to
short circuit of 4WD shift switch.
TF-62, "4WD Shift Switch"
4WD DETECT SWITCH
[P1814]
Improper signal from wait detection switch is input due to open or
short circuit.
TF-66, "Wait Detection Switch"
PNP SW/CIRC
[P1816]
When A/T PNP switch signal is malfunction or communication
error between the vehicles.TF-69, "PNP Switch Signal
(TCM)"
SHIFT ACTUATOR
[P1817]

Motor does not operate properly due to open or short circuit in
actuator motor.

Malfunction is detected in the actuator motor. (When 4WD shift
switch is operated and actuator motor is not operated)

Malfunction is detected in transfer shift high relay and transfer
shift low relay.TF-70, "
Actuator Motor"
SHIFT ACT POSI SW
[P1818]
Improper signal from actuator position switch is input due to open
or short circuit.

Malfunction is detected in the actuator position switch.
TF-77, "
Actuator Position
Switch"

TF-46
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
CAUTION:

If “CAN COMM CIRCUIT [U1000]” is displayed with other DTCs, first perform the trouble diagnosis for CAN communica-
tion 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 ” posi-
tion on A/T PNP switch. When there is nothing wrong with the electrical system, check the hydraulic system.
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-81, "
Transfer Control Device"
Malfunction is detected in transfer shut off relay.
TF-54, "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-85, "
Engine Speed Signal
(ECM)"
DUTY SOLENOID
[P1822]
Proper voltage is not applied to clutch pressure solenoid valve
due to open or short circuit.
TF-86, "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-91, "2-4WD Solenoid"
MOTOR RELAY
[P1824]
Motor does not operate properly due to open or short circuit in
transfer motor or motor relay.TF-95, "Transfer Motor"
OIL TEMP SEN
[P1826]
Signal voltage from fluid temperature sensor is abnormally high
(Transfer fluid temperature is abnormally low) while driving.TF-102, "Transfer Fluid Temper-
ature"
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-105, "
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-108, "
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 abnor-
mally high or low.TF-111, "
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
communication.
TF-111, "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
communication.TF-112, "VDC Operation Signal
(ABS)"
TCS OP SIG
[P1832]
Malfunction is detected in TCS operation signal that is output
from ABS through CAN communication.
TF-112, "TCS Operation Signal
(ABS)"
CAN COMM CIRCUIT
[U1000]
Malfunction has been detected from CAN communication line.
TF-113, "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