2006 INFINITI QX56 4WD

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

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Revision: November 2009 2006 QX56
WORK SUPPORT
When there is no problem with transfer and 4WD system, following symptom in “AUTO” mode may be claimed
by a customer.

Vibration when accelerating on a low µ road (snow-covered or icy road)
It is possible to deal with these symptoms by changing “CLUTCH FORCE RELEASE LIMIT VALUE”.
However, be careful when changing the values because it may adversely affect driving performance.
NOTE:
A slight shock is felt at a few hertz as if it were being pushed lightly from behind.
Operation Procedure
1. Perform “CONSULT-II SETTING PROCEDURE ”. Refer to TF-44, "CONSULT-II SETTING PROCEDURE"
.
2. Touch “WORK SUPPORT ”.
3. Select from “CLUTCH/F RLS LIM ADJ ”, screen of data monitor mode is displayed.
T/F F SPEED [km/h] or [mph] ×–×Displayed, but do not use.
A/T R SPEED [km/h] or [mph] ×–×Output shaft revolution signal (Revolution
sensor) calculated by TCM.
Signal input with CAN communication line.
AT GEAR POSI [1/2/3/4/5] ×–×A/T actual gear position is displayed.
Voltage [V] ––×The value measured by the voltage probe is
displayed.
Frequency [Hz] ––×
The value measured by the pulse probe is
displayed.
DUTY-HI (high) [%]
––×
DUTY-LOW (low) [%] ––×
PLS WIDTH-HI [msec] ––×
PLS WIDTH-LOW [msec] ––×
Monitored item (Unit)
Monitor item selection
Remarks
ECU INPUT
SIGNALS MAIN
SIGNALS SELEC-
TION FROM MENU

TF-50
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
Clutch Force Release Limit Adjustment
1. Current CLUTCH FORCE RELEASE LIMIT value “0.3 kgm”
appears under “CONDITION SETTING ” on CONSULT-II display.
2. Touch “1.2” on the display.
3. Display changes to “NOW ADJUSTING” in a short time.
4. When clutch force release limit value is set to “1.2 kgm”, current
value “0.3 kgm ” shown on display will be replaced by “1.2 kgm”
and “ADJUSTMENT COMPLETE ” will appear at the same time.
Clutch force release limit value setting is now complete.
Self-diagnostic ProcedureEDS002HL
SELF-DIAGNOSTIC PROCEDURE (WITH CONSULT-II)
Refer to TF-45, "SELF-DIAG RESULT MODE" .
SELF-DIAGNOSTIC PROCEDURE (WITHOUT CONSULT-II)
Description
If the engine starts when there is something wrong with the 4WD system, the 4WD warning lamp turns ON or
flickers in the combination meter. When the system functions properly, the warning lamp turns ON when the
ignition switch is turned to “ON”, and it turns OFF after engine starts. To locate the cause of a problem, start
the self-diagnosis function. The 4WD warning lamp in the combination meter will indicate the problem area by
flickering according to the self-diagnostic results. As for the details of the 4WD warning lamp flickering pat-
terns, refer to TF-51, "
Diagnostic Procedure" .
1.2 kg-m : Tight corner braking symptom is allevi-
ated. However, vibration may occur when
accelerating on a low µ road (icy road, etc.).
0.3 kg-m : Initial set value.
0.2 kg-m : Do not set to this value because the tight corner braking symptom will get worse.
SMT968D
SMT969D
SMT970D

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Revision: November 2009 2006 QX56
Diagnostic Procedure
1. Warm up engine.
2. Move A/T selector lever to “P” position.
3. Turn 4WD shift switch to “2WD” position.
4. Turn ignition switch “ON” and “OFF ” at least twice, and then turn ignition switch “OFF”.
5. Turn 4WD shift switch to “AUTO” position.
6. Turn ignition switch “ON”. (Do not start engine.)
7. 4WD warning lamp ON. If 4WD warning lamp does not turn ON, refer to TF-121, "
4WD Warning Lamp Does Not Turn ON" .
8. Move A/T selector lever to “R” position.
9. Turn 4WD shift switch to “2WD”, “AUTO ” and “2WD ” in order.
10. Move A/T selector lever to “D” position.
11. Turn 4WD shift switch to “4H”, “AUTO ” and “4H” in order.
12. Move A/T selector lever to “N” position.
13. Turn 4WD shift switch to “AUTO” position.
14. Move A/T selector lever to “P” position.
15. Read the flickering of 4WD warning lamp. Refer to TF-51, "
Judgement Self-diagnosis" .
Judgement Self-diagnosis
When a malfunction is detected, the malfunction route is indicated by flickering of the 4WD warning lamp.
PDIA0227E
Flickering pattern or
flickering condition Items
Malfunction Check items
2 Output shaft revolution
signal (from TCM)

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)"
3
Clutch pressure sole-
noid signal
Proper voltage is not applied to clutch pressure solenoid
valve due to open or short circuit. TF-86, "Clutch Pres-
sure Solenoid"
4
2-4WD solenoid signal
Proper voltage is not applied to 2-4WD solenoid valve
due to open or short circuit. TF-91, "2-4WD Sole-
noid"
5
Transfer motor
Motor does not operate properly due to open or short cir-
cuit in transfer motor or motor relay. TF-95, "Transfer Motor"
6
Vehicle speed signal
(from ABS)

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

Improper signal is input while driving. TF-58, "
Vehicle Speed
Sensor (ABS)"
7
CAN communication
Malfunction has been detected from CAN communica-
tion line. TF-113, "CAN Commu-
nication Line"
8
AD converter
AD converter system of transfer control unit is malfunc-
tioning. TF-54, "Power Supply
Circuit For Transfer
Control Unit"

TF-52
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
9Transfer fluid tempera-
ture

Signal voltage from fluid temperature sensor is abnor-
mally high (Transfer fluid temperature is abnormally low)
while driving. TF-102, "Transfer Fluid
Temperature"
10
Neutral-4LO switch
Improper signal from neutral-4LO switch is input due to
open or short circuit. TF-59, "Neutral-4LO
Switch"
11
Clutch pressure switch

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 Pres-
sure Switch"
12
Line pressure switch

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"
13
Engine speed signal
(from ECM)

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)"
14
Throttle position sen-
sor (from ECM)

Malfunction is detected in accelerator pedal position sig-
nal that is output from ECM through CAN communica-
tion.

Signal voltage from accelerator pedal position sensor is
abnormally high or low. TF-111, "
Throttle Posi-
tion Signal (ECM)"
15
Power supply
Power supply voltage for transfer control unit is abnor-
mally low while driving. TF-54, "Power Supply
Circuit For Transfer
Control Unit"
16
4WD shift switch
More than two switch inputs are simultaneously detected
due to short circuit of 4WD shift switch. TF-62, "4WD Shift
Switch"
17
ABS operation signal
(from ABS)

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)"
18
Wait detection switch
Improper signal from wait detection switch is input due to
open or short circuit. TF-66, "Wait Detection
Switch"
19
Actuator motor

Motor does not operate properly due to open or short cir-
cuit 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", TF-54, "Power
Supply Circuit For
Transfer Control Unit"
20
Actuator position
switch

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 Posi-
tion Switch"
21
Actuator circuit

Transfer control device actuator circuit is shorted or
open. (Malfunctions are detected when motor relay cir-
cuit is open/shorted or relay transfer shift circuit is open/
shorted.)

Malfunction occurs in transfer control device drive circuit. TF-81, "
Transfer Con-
trol Device"

Malfunction is detected in transfer shut off relay.
TF-54, "
Power Supply
Circuit For Transfer
Control Unit"
22
VDC operation signal
(from VDC)

Malfunction is detected in VDC operation signal that is
output from ABS actuator and electric unit (control unit)
through CAN communication. TF-112, "VDC Opera-
tion Signal (ABS)"
23
TCS operation signal
(from TCS)

Malfunction is detected in TCS operation signal that is
output from ABS actuator and electric unit (control unit)
through CAN communication. TF-112, "TCS Opera-
tion Signal (ABS)"
Flickering pattern or
flickering condition Items
Malfunction Check items

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Revision: November 2009 2006 QX56
CAUTION:

If “CAN communication” is displayed with other DTCs, first perform the trouble diagnosis for CAN communication line.

If “ABS operation signal”, “VDC operation signal" or “TCS operation signal" is displayed, first perform the trouble diag-
nosis for ABS system.

If “Output shaft revolution signal” is displayed, first perform the trouble diagnosis for A/T system.
NOTE:

If "actuator position switch" or “actuator circuit ” is displayed, first erase self-diagnostic results. ("Actuator position switch" or “actua-
tor circuit ” may be displayed after installing transfer control unit or transfer assembly.)

If “clutch pressure switch ” or “line pressure switch” is displayed only while driving in reverse, check the continuity of “R ” position on
A/T PNP switch. When there is nothing wrong with the electrical system, check the hydraulic system.
ERASE SELF-DIAGNOSIS

In order to make it easier to find the cause of hard-to-duplicate malfunctions, malfunction information is
stored into the control unit as necessary during use by the user. This memory is not erased no matter how
many times the ignition switch is turned ON and OFF.

However, this information is erased by turning ignition switch “OFF” after performing self-diagnostics or by
erasing the memory using the CONSULT-II.
24 PNP switch signal
(from TCM)
When A/T PNP switch signal is malfunctioning or com-
munication error between the vehicles. TF-69, "PNP Switch
Signal (TCM)"
Repeats flickering
every 2 to 5 sec.
—
Circuits that the self-diagnosis covers have no malfunction. —
Repeats flickering
every 0.25 sec. Data erase display

Power supply failure of memory back-up.

Battery performance is poor. TF-54, "
Power Supply
Circuit For Transfer
Control Unit"
No flickering
PNP switch or 4WD
shift switch
PNP switch or 4WD shift switch circuit is shorted or
open. TF-69, "PNP Switch
Signal (TCM)",
TF-62,
"4WD Shift Switch"
Flickering pattern or
flickering condition Items
Malfunction Check items

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Revision: November 2009 2006 QX56
COMPONENT INSPECTION
1. Turn ignition switch “OFF”. (Stay for at least 5 seconds.)
2. Remove transfer shut off relay. Refer to TF-22, "
Location of Electrical Parts" .
3. Apply 12V direct current between transfer shut off relay termi- nals 1 and 2.
4. Check continuity between relay terminals 3 and 5.
5. If NG, replace the transfer shut off relay. Refer to TF-22, "
Loca-
tion of Electrical Parts" .
Transfer Control UnitEDS002I5
DIAGNOSTIC PROCEDURE
1. INSPECTION START
Do you have CONSULT-II?
YES or NO
YES >> GO TO 2.
NO >> GO TO 3.
2. PERFORM SELF-DIAGNOSIS (WITH CONSULT-II)
With CONSULT-II
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “SELF-DIAG RESULTS ” mode for “ALL MODE AWD/4WD ” with CONSULT-II.
3. Touch “ERASE”.
4. Turn ignition switch “OFF” and wait at least 10 seconds.
5. Perform the self-diagnosis again.
Is the
“CONTROL UNIT 1 [P1802]”, “CONTROL UNIT 2 [P1803]”, “CONTROL UNIT 3 [P1804]” or “CONTROL
UNIT 4 [P1809]” displayed?
YES >> Replace transfer control unit. Refer to TF-132, "Removal and Installation" .
NO >> Inspection End.
3. PERFORM SELF-DIAGNOSIS (WITHOUT CONSULT-II)
Without CONSULT-II
1. Perform the self-diagnosis and then erase self-diagnostic results. Refer to TF-50, "
SELF-DIAGNOSTIC
PROCEDURE (WITHOUT CONSULT-II)" and TF-53, "ERASE SELF-DIAGNOSIS" .
2. Perform the self-diagnosis again.
Do the self-diagnostic results indicate AD converter?
YES >> Replace transfer control unit. Refer to TF-132, "Removal and Installation" .
NO >> Inspection End.
Condition Continuity
12V direct current supply between terminals 1 and 2 Yes
OFF No
SCIA1245E

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Neutral-4LO SwitchEDS002I8
CONSULT-II REFERENCE VALUE IN DATA MONITOR MODE
Data are reference value.
TRANSFER CONTROL UNIT TERMINALS AND REFERENCE VALUE
Data are reference value and are measured between each terminal and ground.
CAUTION:
When using a circuit tester to measure voltage for inspection, be sure not to extend forcibly any connector terminals.Monitored item
Content ConditionDisplay value
N POSI SW TF [ON/
OFF] Condition of neutral-4LO
switch

Vehicle stopped

Engine running

A/T selector lever “
N”
position

Brake pedal depressed 4WD shift switch: 2WD,
AUTO or 4H
OFF
4WD shift switch: 4H to
4LO (While actuator
motor is operating.) OFF
→ ON
4WD shift switch: 4LO to
4H (While actuator motor
is operating.) ON →
OFF
4WD shift switch: 4LO ON
TerminalWire
color Item
ConditionData (Approx.)
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