2005 INFINITI QX4 4WD

TROUBLE DIAGNOSIS FOR SYMPTOMS
TF-129
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5. CHECK TRANSFER CONTROL UNIT
Check transfer control unit input/output signal. Refer to TF-36, "
Transfer Control Unit Input/Output Signal Ref-
erence Values" .
OK or NG
OK >> Inspection End.
NG >> Check transfer control unit pin terminals for damage or loose connection with harness connector.
If any items are damaged, repair or replace damaged parts.
4WD Warning Lamp Flashes SlowlyEDS002HS
SYMPTOM:
While driving, 4WD warning lamp flashes slowly. (When continuing to flash until turning ignition
switch OFF.)
NOTE:
Slow flashing: 1 time/2 seconds
DIAGNOSTIC PROCEDURE
1. CHECK TIRE
Check the following.

Tire pressure

Wear condition

Longitudinal tire size (There is no difference between longitudinal tires.)
OK or NG
OK >> GO TO 2.
NG >> Repair or replace damaged parts.
2. CHECK TRANSFER FLUID TEMPERATURE
Perform trouble diagnosis for transfer fluid temperature system. Refer to TF-102, "
Transfer Fluid Temperature"
.
OK or NG
OK >> GO TO 3.
NG >> Repair or replace damaged parts.
3. CHECK CLUTCH PRESSURE SWITCH
Perform trouble diagnosis for clutch pressure switch system. Refer to TF-105, "
Clutch Pressure Switch" .
OK or NG
OK >> GO TO 4.
NG >> Repair or replace damaged parts.
4. SYMPTOM CHECK
Check again.
OK or NG
OK >> Inspection End.
NG >> GO TO 5.
5. CHECK TRANSFER CONTROL UNIT
Check transfer control unit input/output signal. Refer to TF-36, "
Transfer Control Unit Input/Output Signal Ref-
erence Values" .
OK or NG
OK >> Inspection End.
NG >> Check transfer control unit pin terminals for damage or loose connection with harness connector.
If any items are damaged, repair or replace damaged parts.

TF-130
TROUBLE DIAGNOSIS FOR SYMPTOMS
Revision: October 20052005 QX56
Heavy Tight-corner Braking Symptom OccursEDS002HT
SYMPTOM:
Heavy tight-corner braking symptom occurs when vehicle is driven in AUTO mode and steering wheel
is turned fully to either side.
DIAGNOSTIC PROCEDURE
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.
1. CHECK SYSTEM FOR CAN COMMUNICATION LINE
Perform self-diagnosis. Refer to TF-50, "
SELF-DIAGNOSTIC PROCEDURE (WITH CONSULT-II)" .
Is "CAN COMM CIRCUIT [U1000]" displayed?
YES >> Perform trouble diagnosis for CAN communication line. Refer to TF-113, "CAN Communication
Line" .
NO >> GO TO 2.
2. CHECK SYSTEM FOR 4WD SHIFT SWITCH
Perform trouble diagnosis for 4WD shift switch system. Refer to TF-62, "
4WD Shift Switch" .
OK or NG
OK >> GO TO 3.
NG >> Repair or replace damaged parts.
3. CHECK ACCELERATOR PEDAL POSITION SIGNAL CIRCUIT
Perform self diagnosis for ECM. Refer to EC-49, "
Emission-related Diagnostic Information" .
Is any malfunction detected by self-diagnosis?
YES >> Check the malfunctioning system.
NO >> GO TO 4.
4. CHECK SYSTEM FOR CLUTCH PRESSURE SOLENOID
Perform trouble diagnosis for clutch pressure solenoid system. Refer to TF-105, "
Clutch Pressure Switch" .
OK or NG
OK >> GO TO 5.
NG >> Repair or replace damaged parts.
5. SYMPTOM CHECK
Check again.
OK or NG
OK >> Inspection End.
NG >> GO TO 6.
6. CHECK TRANSFER CONTROL UNIT
Check transfer control unit input/output signal. Refer to TF-36, "
Transfer Control Unit Input/Output Signal Ref-
erence Values" .
OK or NG
OK >> GO TO 7.
NG >> Check transfer control unit pin terminals for damage or loose connection with harness connector.
If any items are damaged, repair or replace damaged parts.

TROUBLE DIAGNOSIS FOR SYMPTOMS
TF-131
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7. CHECK TRANSFER INNER PARTS
1. Disassemble transfer assembly. Refer to TF-144, "
Disassembly and Assembly" .
2. Check transfer inner parts.
OK or NG
OK >> Inspection End.
NG >> Repair or replace damaged parts.
4WD System Does Not OperateEDS002HU
SYMPTOM:
The vehicle cannot be put into 4WD mode. (Hydraulic system failure)
DIAGNOSTIC PROCEDURE
1. CHECK SYSTEM FOR 4WD SHIFT SWITCH
Perform trouble diagnosis for 4WD shift switch system. Refer to TF-62, "
4WD Shift Switch" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace damaged parts.
2. CHECK SYSTEM FOR CLUTCH PRESSURE SWITCH
Perform trouble diagnosis for clutch pressure switch system. Refer to TF-105, "
Clutch Pressure Switch" .
OK or NG
OK >> GO TO 3.
NG >> Repair or replace damaged parts.
3. SYMPTOM CHECK
Check again.
OK or NG
OK >> Inspection End.
NG >> GO TO 4.
4. CHECK TRANSFER CONTROL UNIT
Check transfer control unit input/output signal. Refer to TF-36, "
Transfer Control Unit Input/Output Signal Ref-
erence Values" .
OK or NG
OK >> GO TO 5.
NG >> Check transfer control unit pin terminals for damage or loose connection with harness connector.
If any items are damaged, repair or replace damaged parts.
5. CHECK TRANSFER INNER PARTS
1. Disassemble transfer assembly. Refer to TF-144, "
Disassembly and Assembly" .
2. Check transfer inner parts.
OK or NG
OK >> Inspection End.
NG >> Repair or replace damaged parts.

TF-132
TRANSFER CONTROL UNIT
Revision: October 20052005 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, "
Instrument Lower Cover 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-138
TRANSFER CONTROL DEVICE
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TRANSFER CONTROL DEVICEPFP:33251
Removal and InstallationEDS0 02 IW
Refer to the figure for transfer control device removal and installation information.
CAUTION:

Change vehicle state to 2WD or AUTO, and then remove and install transfer control device.

Check 4WD shift indicator after installation. Refer to TF-4, "Precautions for Transfer Assembly and
Transfer Control Unit Replacement" .
1. Shift lever 2. Actuator
SDIA2654E

TRANSFER ASSEMBLY
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b. Remove the following from the control valve assembly:

Clutch pressure solenoid valve

Clutch pressure switch

2-4WD shift solenoid valve

Line pressure switch

Transfer fluid temperature sensor
c. Remove the O-rings from each solenoid valve, switch and termi-
nal body.
d. Place the control valve with the lower body facing up. Remove
the two bolts, and then remove the lower body and separator
plate from the upper body.
CAUTION:
Do not drop relief balls. Detach lower body carefully.
e. Make sure the reverse balls, relief balls, relief springs, accumu-
lator pistons and valve springs are securely installed as shown,
and remove them.
f. Remove the retainer plates.
g. Remove each plug (2), control valve (3) and spring (4) from the
upper body (5).

Retainer plate (1)
WDIA0199E
SDIA2125E
SDIA2126E
SDIA2127E
WDIA0284E

TRANSFER ASSEMBLY
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Bearing

Make sure the bearings roll freely and are free from noise, pit-
ting and cracks.
Main Oil Pump
1. Check the inner and outer circumference, tooth face, and side-
face of the inner and outer gears for damage or abnormal wear.
2. Measure the side clearance between the main oil pump housing
edge and the inner and outer gears.
3. Make sure the side clearance is within specification. If the mea-
surement is out of specification, replace the inner and outer
gears with new ones as a set. Refer to TF-163, "
Main Oil Pump"
.
Sub-oil Pump
1. Check the inner and outer circumference, tooth face, and side-
face of the inner and outer gears for damage or abnormal wear.
2. Measure the side clearance between the sub oil pump housing
edge and the inner and outer gears.
3. Make sure the side clearance is within specification. If the mea-
surement is out of specification, replace the inner and outer
gears with new ones as a set. Refer to TF-163, "
Sub-oil Pump" .
Control Valve

Check resistance between the terminals of the clutch pressure
solenoid valve, 2-4WD shift solenoid valve, clutch pressure
switch and the transfer fluid temperature sensor. Refer to TF-90,
"COMPONENT INSPECTION" (clutch pressure solenoid
valve), TF-94, "
COMPONENT INSPECTION" (2-4WD solenoid
valve), TF-107, "
COMPONENT INSPECTION" (clutch pressure
switch) and TF-104, "
COMPONENT INSPECTION" (transfer
fluid temperature sensor).
SDIA2175E
Specification : 0.015 - 0.035 mm (0.0006 - 0.0014 in)
SDIA2174E
Specification : 0.015 - 0.035 mm (0.0006 - 0.0014 in)
SDIA2173E
WDIA0199E

TRANSFER ASSEMBLY
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d. Install the reverse balls, relief balls and relief springs, accumula-
tor pistons and valve springs to the upper body.
e. Install the lower body and separator plate to the upper body.
CAUTION:
Do not reuse separator plates.
f. With the lower body down, tighten the two bolts shown.
g. Apply ATF to the O-rings, and install them to each solenoid
valve, switch and terminal body.
CAUTION:
Do not reuse O-rings.
h. Install the following to the control valve assembly:

Clutch pressure solenoid valve

Clutch pressure switch

2-4WD shift solenoid valve

Line pressure switch

Transfer fluid temperature sensor
10. Apply ATF to lip seals, and install them to the center case.
CAUTION:

Do not reuse lip seals.

There are 2 kinds of lip seals (lip seal of large inner diam-
eter: 5 pieces, lip seal of small inner diameter: 2 pieces).
Confirm their position for installation.
SDIA2126E
WDIA0200E
WDIA0198E
SDIA2123E