2001 INFINITI QX4 air filter

steps 4 through 8 until coolant level no longer drops.
IClean excess coolant from engine.
ÐFLUSHING COOLING SYSTEMÐNBMA0011S031. Open air relief plug.
2. Fill radiator with water until water spills from the air relief holes,
then close air relief plugs. Fill radiator and reservoir tank with
water and reinstall radiator cap.
3. Run engine and warm it up to normal operating temperature.
4. Rev engine two or three times under no-load.
5. Stop engine and wait until it cools down.
6. Drain water.
7. Repeat steps 1 through 6 until clear water begins to drain from
radiator.
SMA803A
Checking Fuel LinesNBMA0012Inspect fuel lines and tank for improper attachment, leaks, cracks,
damage, loose connections, chafing or deterioration.
If necessary, repair or replace faulty parts.
MMA104A
CAUTION:
Tighten high-pressure rubber hose clamp so that clamp end is
3 mm (0.12 in) from hose end.
Tightening torque specifications are the same for all rubber
hose clamps.
Ensure that screw does not contact adjacent parts.
SEF214Y
Changing Fuel FilterNBMA0013WARNING:
Before removing fuel filter, release fuel pressure from fuel line.
WITH CONSULT-IINBMA0013S011. Turn ignition switch ªONº.
2. Perform ªFUEL PRESSURE RELEASEº in ªWORK SUP-
PORTº mode with CONSULT-II.
3. Start engine.
4. After engine stalls, crank engine two or three times to release
all fuel pressure.
ENGINE MAINTENANCE
Changing Engine Coolant (Cont'd)
MA-16

5. Turn ignition switch ªOFFº.
SMA861C
6. Loosen fuel hose clamps.
7. Replace fuel filter.
IBe careful not to spill fuel over engine compartment. Place
a shop towel to absorb fuel.
IUse a high-pressure type fuel filter. Do not use a synthetic
resinous fuel filter.
IWhen tightening fuel hose clamps, refer to ªChecking Fuel
Linesº.
SMA869C
WITHOUT CONSULT-IINBMA0013S021. Remove fuel pump fuse located in fuse box.
2. Start engine.
3. After engine stalls, crank it two or three times to release all fuel
pressure.
4. Turn ignition switch ªOFFº and install fuel pump fuse.
SMA861C
5. Loosen fuel hose clamps.
6. Replace fuel filter.
IBe careful not to spill fuel over engine compartment. Place
a shop towel to absorb fuel.
IUse a high-pressure type fuel filter. Do not use a synthetic
resinous fuel filter.
IWhen tightening fuel hose clamps, refer to ªChecking Fuel
Linesº.
SMA095D
Changing Air Cleaner FilterNBMA0014VISCOUS PAPER TYPENBMA0014S01The viscous paper type filter does not need cleaning between
replacement intervals.
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ENGINE MAINTENANCE
Changing Fuel Filter (Cont'd)
MA-17

SMA010
2. Clean oil filter mounting surface on cylinder block. Coat rubber
seal of new oil filter with engine oil.
SMA702C
3. Screw in the oil filter until a slight resistance is felt, then tighten
an additional 2/3 turn.
4. Add engine oil.
Refer to MA-18, ªChanging Engine Oilº.
IClean excess oil from engine.
SMA098D
Changing Spark PlugsNBMA00171. Remove engine cover.
2. Remove throttle wires.
3. Remove air duct with air cleaner assembly.
4. Disconnect harness connectors and harness brackets around
ignition coil sides.
5. Remove throttle body. (Only when removing the No. 4 cylinder
spark plug)
6. Disconnect ignition coil harness connectors.
7. Loosen ignition coil fixing bolts and pull out coil from intake
manifold connector.
Ignition coil:
: 8.5 - 10.7 N´m (0.86 - 1.1 kg-m, 75 - 95 in-lb)
SEM294A
8. Check type and gap of new spark plug.
Spark plug type:
Symbol Make
Standard type PLFR5A-11 NGK
Cold type PLFR6A-11 NGK
Hot type PLFR4A-11 NGK
Gap (Nominal): 1.1 mm (0.043 in)
Spark plug:
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ENGINE MAINTENANCE
Changing Oil Filter (Cont'd)
MA-19

LINE PRESSURE SWITCH...........................................83
Diagnostic Procedure ................................................83
ABS OPERATION SIGNAL...........................................86
Diagnostic Procedure ................................................86
DATA ERASE/DISPLAY...............................................88
Diagnostic Procedure ................................................88
SHIFT ACTUATOR........................................................89
Diagnostic Procedure ................................................89
SHIFT ACTUATOR POSITION SWITCH......................92
Diagnostic Procedure ................................................92
SHIFT ACTUATOR CIRCUIT........................................94
Diagnostic Procedure ................................................94
TROUBLE DIAGNOSES FOR SYMPTOMS.................98
Symptom 1. 4WD Shift Indicator Lamp Does Not
Turn ON .....................................................................98
Symptom 2. 4WD Warning Lamp Does Not Turn
ON............................................................................100
Symptom 3. 4WD Shift Indicator Lamp Does Not
Turn OFF .................................................................102
Symptom 4. ATP Warning Lamp Does Not Turn
ON............................................................................102
Symptom 5. 4LO Indicator Lamp Does Not Turn
ON............................................................................104
Symptom 6. 4WD Shift Indicator Lamp Does Not
Indicate²4H²............................................................106
Symptom 7. 4WD Shift Indicator Lamp Repeats
Flickering..................................................................107
Symptom 8. Tight Corner Braking Symptom...........108
Symptom 9. 4WD System Does Not Operate.........109
COMPONENT INSPECTION....................................... 111
4WD Shift Switch ..................................................... 111
2-4WD Shift Solenoid Valve and Transfer Fluid
Temperature Sensor ................................................ 111
4WD Solenoid Valve, Clutch Pressure Switch
and Line Pressure Switch........................................ 111
Front Revolution Sensor .......................................... 112
Transfer Dropping Resistor...................................... 112
ATP Switch, Neutral-4LO Switch and Wait
Detection Switch ...................................................... 112
Transfer Motor ......................................................... 113
Transfer Motor Relay ............................................... 113
Transfer Sub-harness .............................................. 113
FRONT REVOLUTION SENSOR SUB-HARNESS
CONNECTOR
........................................................ 113
TRANSFER SWITCH ASSEMBLY SUB-HARNESS
CONNECTOR
........................................................ 114
TRANSFER TERMINAL CORD ASSEMBLY SUB-
HARNESS CONNECTOR
....................................... 114
Transfer Shift Relay (High & low) ............................ 114
Actuator & Actuator Position Switch ........................ 115
ACTUATOR........................................................... 115
ACTUATOR POSITION SWITCH............................ 115
ON-VEHICLE SERVICE.............................................. 116
Replacing Oil Seal ................................................... 116
FRONT CASE OIL SEAL........................................ 116
SHIFT SHAFT OIL SEAL........................................ 117
REAR OIL SEAL.................................................... 117
Transfer Motor ......................................................... 117
REMOVAL............................................................. 117
INSTALLATION...................................................... 117
Transfer Oil Filter ..................................................... 118
REMOVAL............................................................. 118
INSTALLATION...................................................... 118
REMOVAL AND INSTALLATION............................... 119
Removal ................................................................... 119
Installation ................................................................ 119
OVERHAUL.................................................................120
Transfer Gear Control ..............................................120
Transfer Components ..............................................121
DISASSEMBLY............................................................123
Rear Case................................................................123
DISASSEMBLY......................................................123
Center Case.............................................................123
DISASSEMBLY......................................................123
Front Case ...............................................................133
DISASSEMBLY......................................................133
REPAIR FOR COMPONENT PARTS.........................137
Front Case ...............................................................137
INSPECTION.........................................................137
Center Case.............................................................138
INSPECTION.........................................................138
ASSEMBLY..................................................................141
Front Case ...............................................................141
ASSEMBLY...........................................................141
Center Case.............................................................145
ASSEMBLY...........................................................145
Final Assembly.........................................................153
SERVICE DATA AND SPECIFICATIONS (SDS).......157
General Specifications .............................................157
Inner Gear and Outer Gear .....................................157
SUB-OIL PUMP.....................................................157
MAIN OIL PUMP....................................................157
Control Valve ...........................................................157
VALVE..................................................................157
SPRING................................................................157
Clutch .......................................................................158
DRIVE PLATE.......................................................158
DRIVEN PLATE.....................................................158
RETURN SPRING..................................................158
RETAINING PLATE................................................158
Seal Ring (Mainshaft side) ......................................159
Bearing Race (Thrust needle bearing side) ............159
Snap Ring (Sun gear side) ......................................159
CONTENTS(Cont'd)
TF-2

Symptom 9. 4WD System Does Not Operate=NBTF0037SYMPTOM: The vehicle cannot be put into 4WD mode.
(Hydraulic system failure)
1 CHECK INPUT SIGNAL
With CONSULT-II
1. Select ªECU INPUT SIGNALSº in Data Monitor.
2. Read out the ON/OFF status of ªCLUTCH PRES SWº.
SMT977D
Without CONSULT-II
Check voltage between transfer control unit harness connector terminal 34 and body ground.
Refer to ªTRANSFER CONTROL UNIT INSPECTION TABLEº, ªTROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONº,
TF-55.
OK or NG
OK©1. Check transfer fluid level.
2. Disassemble transfer unit and check the following.
ITransfer motor
IMain oil pump assembly
ISub-oil pump assembly
IOil strainer
IControl valve assembly
I2-4WD shift solenoid valve
IOil filter element
ILip seal
IStrainer O-ring
IMain oil pump drive gear
ISeal ring
ID-ring
IClutch piston
IClutch assembly
NG©GO TO 2.
2 CHECK CLUTCH PRESSURE CIRCUIT
Check clutch pressure switch circuit.
Refer to ªDiagnostic Procedureº, ªCLUTCH PRESSURE SWITCHº, TF-80.
OK or NG
OK©GO TO 3.
NG©Check, repair or replace faulty parts.
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TROUBLE DIAGNOSES FOR SYMPTOMS
Symptom 9. 4WD System Does Not Operate
TF-109

SMT945C
Control ValveNBTF0081S04ICheck oil filter screen for damage. If any is found, replace with
new one.
SMT946CA
ICheck resistance between terminals of 4WD solenoid valve,
2-4WD shift solenoid valve and transfer fluid temperature sen-
sor.
Resistance:
Refer to ªCOMPONENT INSPECTIONº, TF-111.
SMT947C
ICheck sliding faces of control valves and plugs for abnormal-
ity. If any is found, replace the control valve assembly with new
one.
CAUTION:
Replace control valve body together with clutch return spring
as a set.
Control valve:
Refer to SDS, TF-157.
SMT948C
ICheck each control valve spring for damage or distortion, and
also check its free length, outer diameter and wire diameter. If
any damage or fatigue is found, replace control valve body with
new one.
IReplace control valve body together with clutch return
spring as a set.
Inspection standard:
Refer to SDS, TF-157.
SMT949C
ClutchNBTF0081S05ICheck drive plate and driven plate facings for damage, cracks
or other abnormality. If any, replace with new one.
ICheck the thickness of drive plate and driven plate facings.
Inspection standard:
Refer to SDS, TF-158.
CAUTION:
IMeasure facing thickness at 3 points to take an average.
ICheck all the drive and driven plates.
ICheck return spring for damage or deformation.
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REPAIR FOR COMPONENT PARTS
Center Case (Cont'd)
TF-139

SMT928C
SMT926C
Control ValveNBTF0083S041. Clean upper body, control valves and springs with cleaning
agent, and apply air blow.
2. Dip control valves in ATF, and apply ATF to the valve-mount-
ing area of upper body.
3. Install each control valve, spring, and plug to upper body, and
fix it with retainer plates.
CAUTION:
ITo insert control valves into upper body, place upper body
on a level surface in order to prevent flaw or damage.
IMake sure each control valve is smoothly inserted.
4. Install reverse balls, relief balls and relief springs, accumula-
tor pistons, valve springs and two filters to upper body.
SMT925C
5. Install lower body and separator plate to upper body.
IDo not reuse separator plates.
SMT962CA
6. With lower body down, tighten two bolts in the position shown
in the figure.
7. Apply ATF or petroleum jelly to new O-ring, and install it to
2-4WD shift solenoid valve, terminal body, line pressure switch
and 4WD solenoid valve. Install them to control valve assem-
bly.
IDo not reuse O-rings.
SMT922CA
8. Apply ATF or petroleum jelly to lip seals, and install them to
center case.
IDo not reuse lip seals.
IThere are 2 kinds of lip seals (lip seal of large inner diam-
eter: 5 pieces, lip seal of small inner diameter: 2 pieces).
Confirm the position before installation.
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ASSEMBLY
Center Case (Cont'd)
TF-147