2001 INFINITI QX4 IDX

2 CHECK TRANSFER CONTROL UNIT GROUND CIRCUIT
1. Turn ignition switch ªOFFº, and disconnect transfer control unit connector.
2. Check for continuity between transfer control unit body-side connector terminals 6, 45 and body ground.
Continuity should exist.
OK or NG
OK©GO TO 3.
NG©Check the following.
IContinuity between transfer control unit and body ground
3 CHECK 4LO INDICATOR LAMP CIRCUIT
Disconnect battery negative terminal (þ) and check the following items:
1. Check condition of 4LO indicator lamp.
2. Check continuity between battery and 4LO indicator lamp.
3. Check continuity between 4LO indicator lamp and transfer control unit connector terminal 12.
4. Check condition of ATP switch.
5. Check condition of neutral-4LO switch.
6. Check continuity between neutral-4LO switch ground terminal 6 and body ground.
OK or NG
OK©GO TO 4.
NG©Check the following.
I4LO indicator lamp
INeutral-4LO switch
Refer to ªATP Switch, Neutral-4LO Switch and Wait Detection Switchº, ªCOMPONENT
INSPECTIONº, TF-112.
4 CHECK PROCEDURES FROM THE BEGINNING
Check again.
OK or NG
OK©INSPECTION END
NG©1. Perform transfer control unit input/output signal inspection. Refer to ªTRANSFER
CONTROL UNIT INSPECTION TABLEº, ªTROUBLE DIAGNOSIS Ð GENERAL
DESCRIPTIONº, TF-55.
2. If NG, recheck transfer control unit pin terminals for damage or loose connection with
harness connector.
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TROUBLE DIAGNOSES FOR SYMPTOMS
Symptom 5. 4LO Indicator Lamp Does Not Turn ON (Cont'd)
TF-105

Symptom 7. 4WD Shift Indicator Lamp Repeats
Flickering
=NBTF0035SYMPTOM: 4WD shift indicator lamp keeps flickering.
1 CHECK 4WD SHIFT INDICATOR LAMP
SMT958D
1. Set 4WD shift switch to ª2WDº position.
2. Move vehicle forward and backward. Or drive straight increasing or decreasing speed under 20 km/h (12 MPH).
3. Does 4WD shift indicator lamp keep flickering?
YesorNo
Ye s©GO TO 2.
No©INSPECTION END
2 CHECK TIGHT CORNER BRAKING SYMPTOM
Drive vehicle at speed under 20 km/h (12 MPH), turning steering wheel to the limit. Does tight corner braking symptom
occur?
YesorNo
Ye s©GO TO 3.
No©GO TO 4.
3 CHECK 4WD SHIFT INDICATOR LAMP
Does the 4WD shift indicator lamp keep flickering when the front wheels are jacked up?
YesorNo
Ye s©Check transfer unit operating system.
No©Check tires.
4 CHECK 4WD WARNING LAMP
Does 4WD warning lamp flicker? (4WD shift indicator lamp is turned OFF.)
YesorNo
Ye s©Perform self-diagnoses. Refer to ªTrouble Diagnosis without CONSULT-IIº, TF-27.
No©GO TO 5.
5 CHECK 4WD SHIFT INDICATOR LAMP
Does 4WD shift indicator lamp keep flickering?
YesorNo
Ye s©Check again.
No©INSPECTION END
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TROUBLE DIAGNOSES FOR SYMPTOMS
Symptom 7. 4WD Shift Indicator Lamp Repeats Flickering
TF-107

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

NBTF0038
SMT858D
4WD Shift SwitchNBTF0038S01Check continuity between each terminal.
Terminals Switch position Continuity
1-22WD Yes
Except 2WD No
1-3,1-4AUTO Yes
Except AUTO No
1-4,1-54H Yes
Except 4H No
1-4,1-64LO Yes
Except 4LO No
SMT079D
2-4WD Shift Solenoid Valve and Transfer Fluid
Temperature Sensor
NBTF0038S02Measure resistance between terminals of transfer terminal cord
assembly sub-harness connector located on rear-right of transfer
unit.
Component parts Terminals Resistance
2-4WD shift solenoid valve 4 - 5Approx. 20ÉC (68ÉF):
Approx. 22.8 - 25.2W
Transfer fluid temperature
sensor2-3Approx. 20ÉC (68ÉF): Approx. 2.5 kW
Approx. 80ÉC (176ÉF): Approx. 0.3
kW
SMT080D
4WD Solenoid Valve, Clutch Pressure Switch
and Line Pressure Switch
NBTF0038S03Measure resistance between terminals of transfer terminal cord
assembly sub-harness connector located on rear-right of transfer
unit.
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COMPONENT INSPECTION
4WD Shift Switch
TF-111

Switch Terminals4WD shift switch position
4H (N) 4LO
ATP switch 8 - 9No conti-
nuityContinuityNo conti-
nuity
Neutral-4LO
switch12 - 13 No continuity Continuity
Wait detection
switch10-11No continuity Continuity
(Note)
+---------------------------
NOTE:
When shifting from ª4LOº to ª4Hº, continuity exists while ªWaitº function is operat-
ing. (No continuity exists when ªWaitº function is canceled.)
SMT082D
Transfer MotorNBTF0038S05Apply battery voltage directly to transfer motor assembly sub-har-
ness connector located on rear-right of transfer unit. (Positive: Ter-
minal 14, Negative: Terminal 15)
Transfer motor should operate.
SMT085D
Transfer Motor RelayNBTF0038S081. Apply battery voltage directly to terminals 3 and 4.
2. Check continuity between terminals 1 and 2.
Condition Continuity (1 - 2)
Battery voltage is applied Yes
No voltage is applied No
SMT086DB
Transfer Sub-harnessNBTF0038S09FRONT REVOLUTION SENSOR SUB-HARNESS
CONNECTOR
NBTF0038S0901Check continuity between terminals shown in the figure.
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COMPONENT INSPECTION
ATP Switch, Neutral-4LO Switch and Wait Detection Switch (Cont'd)
TF-113

SMT812D
Actuator & Actuator Position SwitchNBTF0038S11ACTUATORNBTF0038S1101Operation & resistance check
IApply battery voltage directly to actuator assembly.
Operating check Battery positive terminal Battery negative terminal
143
234
Check Approx. 0.2W(When the motor is not operated.)
SMT838D
ACTUATOR POSITION SWITCHNBTF0038S1102Continuity check
Continuity checkBattery positive
terminalBattery negative
terminalContinuity
14 3 1-5
23 4 2-5
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COMPONENT INSPECTION
Actuator & Actuator Position Switch
TF-115

SMT808D
SHIFT SHAFT OIL SEALNBTF0068S021. Remove front propeller shaft. Refer to PD-6, ªRemoval and
Installationº.
2. Remove companion flange. Refer to ªFRONT CASE OIL
SEALº, TF-116.
3. Remove actuator lever from transfer outer shift lever. Then
remove outer shift lever.
SMT491A
4. Remove shift shaft oil seal.
IBe careful not to damage cross shaft.
SMT805C
5. Install shift shaft oil seal.
IBefore installing, apply multi-purpose grease to seal lip.
6. Install transfer control linkage.
7. Install companion flange. Refer to ªFRONT CASE OIL SEALº,
TF-116.
8. Install front propeller shaft.
SMT892C
REAR OIL SEALNBTF0068S031. Remove rear propeller shaft. Refer to PD-6, ªRemoval and
Installationº.
2. Remove rear oil seal.
3. Install rear oil seal.
IBefore installing, apply multi-purpose grease to seal lip.
4. Install rear propeller shaft.
SMT874C
Transfer Motor
REMOVALNBTF00691. Disconnect transfer motor harness connector.
2. Remove breather pipe from transfer motor.
3. Remove bolts to detach transfer motor.
IAfter removing transfer motor, be sure to replace O-ring
with new one.
INSTALLATIONNBTF00701. Apply petroleum jelly or ATF to O-ring.
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ON-VEHICLE SERVICE
Replacing Oil Seal (Cont'd)
TF-117

SMT897C
RemovalNBTF00731. Remove exhaust front and rear tubes. Refer to FE-8,
ªEXHAUST SYSTEMº.
2. Remove front and rear propeller shaft. Refer to PD-6,
ªRemoval and Installationº.
3. Insert plug into rear oil seal after removing propeller shaft.
IBe careful not to damage spline, sleeve yoke and rear oil
seal, when removing propeller shaft.
4. Disconnect neutral-4LO switch, front revolution sensor, ATP
switch, transfer motor and 4WD shift switch harness connec-
tors.
SMT808D
5. Remove center console and A/T control device.
6. Remove floor panel for transfer.
7. Remove upper side fixing bolt for A/T and TF.
8. Remove actuator lever from transfer outer shift lever and
remove sub-oil pump from transfer.
9. Remove remaining fixing bolt for AT and TF.
SMT899C
SMT871C
10. Remove transfer from transmission.
WARNING:
Support transfer while removing it.
SMT872C
InstallationNBTF0074ITighten bolts securing transfer.
Bolt length:
45 mm (1.77 in)
Tightening torque:
: 31 - 42 N´m (3.2 - 4.3 kg-m, 23 - 31 ft-lb)
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REMOVAL AND INSTALLATION
Removal
TF-119