2001 INFINITI QX4 Ac system

SMT968D
1. Current CLUTCH FORCE RELEASE LIMIT value ª0.3 kg-mº
appears under ªCONDITION SETTINGº on CONSULT-II dis-
play.
2. Touch ª1.2º on the display.
SMT969D
3. Display changes to ªNOW ADJUSTINGº in a short time.
SMT970D
4. When clutch force release limit value is set to ª1.2 kg-mº, cur-
rent value ª0.3 kg-mº shown on display will be replaced by ª1.2
kg-mº and ªADJUSTING COMPLETEº will appear at the same
time. Clutch force release limit value setting is now complete.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Trouble Diagnosis with CONSULT-II (Cont'd)
TF-40

IntroductionNBTF0013DESCRIPTIONNBTF0013S01When a malfunction (indicated by the 4WD warning lamp illumination) occurs, collect information first from the
customer about how the malfunction occurs. Then, proceed with the diagnosis presuming it is the cause. Also
inspect the electrical system, paying close attention to other possibilities such as fluid level and leaks.
All-mode 4WD transfer is controlled by transfer control unit and sensors.
If a malfunction occurs in the all-mode 4WD system, the 4WD warning lamp lights up to inform of the system
malfunction. There are two ways to identify the cause of the malfunction.
1) Performing the self-diagnosis. (The 4WD warning lamp will indicate what kind of malfunction has occurred
by flickering.)
2) Performing diagnosis using CONSULT-II.
DIAGNOSTIC WORKSHEETNBTF0013S02Information from CustomerNBTF0013S0201KEY POINTS
WHAT..... Vehicle model
WHEN..... Date, Frequencies
WHERE..... Road conditions
HOW..... Operating conditions, Symptoms
Information sheet from customer
Customer name MR/MS Model & Year VIN
Transfer model
ATX14AEngine Mileage
Incident Date Manuf. Date In Service Date
FrequencylContinuouslIntermittent ( times a day)
Symptomsl4WD shift indicator lamp does not turn on.
l4WD warning lamp does not turn on.
l4WD shift indicator lamp does not turn off.
lATP warning lamp does not turn on.
l4LO indicator lamp does not turn on.
l4WD shift indicator lamp does not indicate ª4Hº.
l4WD shift indicator lamp repeats flicking.
lTight corner braking symptom occurs.
l4WD system does not operate.
lOthers.
4WD warning lamplContinuously litlNot lit
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TROUBLE DIAGNOSIS Ð INTRODUCTION
Introduction
TF-41

SMT772D
TRANSFER CONTROL UNIT INSPECTION TABLENBTF0018S02(Data are reference values.)
Terminal
No.Item Condition Judgement standard
12-4WD shift solenoid
valve
&
4WD shift switch is set to ª2WDº
position.Less than 1V
4WD shift switch is set to any posi-
tion other than ª2WDº.Battery voltage
24WD shift indicator lamp
(2WD)
Lamp lights while system is operating
properly.Less than 1V
&
2WD indicator lamp does not come
on.Battery voltage
3 Ground Ð Ð
4Transfer shift relay
(High)While actuator is operating
(4H,4LO)Battery voltage
Actuator does not operate. Less than 1V
5 4WD warning lampLamp comes ON. (when engine is
stopped.)
(Fail-safe condition appears on
display, engine is stopped, actuator
position detection switch is
inoperative, oil temperature is too
high and/or tires of different size are
installed.)Less than 1V
Except above Battery voltage
6 Ground Ð Ð Ð
7 PNP switch (R position)
&
A/T selector lever is set to ªreverseº
position.Battery voltage
A/T selector lever is set to any posi-
tion other than ªreverseº.Less than 1V
8ÐÐÐÐ
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TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Transfer Control Unit Terminals and Reference Value (Cont'd)
TF-55

Terminal
No.Item Condition Judgement standard
31Transfer fluid tempera-
ture sensor
&
At 20ÉC (68ÉF) Approx. 1.5V
At 80ÉC (176ÉF) Approx. 0.5V
32 ABS signalWhen moving, use the CONSULT-II
pulse frequency measuirng func-
tion.*2
CAUTION:
Connect the diagnosis data link
cable to the vehicle diagnosis con-
nector.
*2: A circuit tester cannot be used to
test this item.Refer to the illustration
(SMT973D) at the end of
this section.
33Transfer shift relay
(High)While actuator is operating from ª4Hº
to ª4LOºBattery voltage
Actuator does not operate. Approx. 0V
34 Clutch pressure switch4WD shift switch is set to ªAUTOº or
ª4Hº, then A/T selector lever is set to
ªDº position. (wait detection system:
OFF)Battery voltage
4WD shift switch is set to ª2WDº,
ªAUTOº or ª4Hº, then A/T selector
lever is set to ªDº position. (wait
detection system: ON)Approx. 0V
35 Line pressure switch4WD shift switch is set to ª2WDº,
ªAUTOº or ª4Hº, then A/T selector
lever is set to ªDº position.Battery voltage
Ð Approx. 0V
36 CONSULT-II (RX) Ð Ð Ð
37 Tachometer
ÐRefer to EC-127, ªECM
Inspection Tableº.
38 Front revolution sensor
4WD shift switch is set to ª4Hº posi-
tion. A/T selector lever is set to ªDº
position.Approx. 1V [30 km/h (19
MPH)]
Voltage rises in
response to vehicle
speed.
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Transfer Control Unit Terminals and Reference Value (Cont'd)
TF-58

Terminal
No.Item Condition Judgement standard
39ECM (Throttle position
sensor)
&
Throttle valve is fully open. Approx. 0.5V
Throttle valve is closed. Approx. 4.2V
40 ATP switchA/T selector lever is set to ªPº posi-
tion.Battery voltage
A/T selector lever is set to any posi-
tion other than ªPº.Less than 1V
41Transfer motor relay
monitorTransfer motor relay is ON. Battery voltage
Transfer motor relay is OFF. Less than 1V
42Transfer shift relay
(LOW)While actuator is operating from
ª4LOº to ª4Hº positionBattery voltage
Actuator does not operate. Approx. 0V
43 Wait detection switch4WD shift switch is set to any posi-
tion other than ª4LOº.Battery voltage
4WD shift switch is set to ª4LOº posi-
tion.*3Less than 1V
44Transfer 4LO actuator
switch4WD shift switch is set to any posi-
tion other than ª4LOº. (Actuator: High
position)Battery voltage
4WD shift switch is set to ª4LOº posi-
tion. (Actuator: Low position)Less than 1V
45 Ground Ð Ð Ð
46ÐÐÐÐ
47Power supply (memory
back up)
&Ð Battery voltage
48 CONSULT-II (TX) Ð Ð Ð
*3: While wait detection system is operating, terminal 43 exists battery voltage.
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TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Transfer Control Unit Terminals and Reference Value (Cont'd)
TF-59

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 8. Tight Corner Braking SymptomNBTF0036SYMPTOM: Tight corner braking symptom occurs. (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©Disassemble transfer unit and check the following.
IControl valve assembly
I4WD solenoid valve
I2-4WD shift solenoid valve
IClutch piston
IClutch assembly
NG©GO TO 2.
2 CHECK CLUTCH PRESSURE SWITCH 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.
3 CHECK PROCEDURES FROM THE BEGINNING AGAIN
Check again.
OK or NG
OK©INSPECTION END
NG©Recheck each connector's pin terminals for damage or loose connection.
TROUBLE DIAGNOSES FOR SYMPTOMS
Symptom 8. Tight Corner Braking Symptom
TF-108

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