Engine control INFINITI QX4 2001 Factory Service Manual

6. If rack sliding force is not within specification, overhaul steer-
ing gear assembly.
7. If rack sliding force is OK, inspect steering column. Refer to
ªInspectionº, ªSTEERING WHEEL AND STEERING
COLUMNº, ST-14.
SST834-F
Checking Hydraulic SystemNBST0015Before starting, check belt tension, driving pulley and tire pressure.
1. Set Tool. Open shut-off valve. Then bleed air.
Refer to ªBleeding Hydraulic Systemº, ST-9.
2. Run engine, at idle speed or 1,000 rpm.
Make sure fluid temperature in reservoir tank rises to 60 to
80ÉC (140 to 176ÉF).
WARNING:
Warm up engine with shut-off valve fully opened. If engine is
started with shut-off valve closed, fluid pressure in the power
steering pump increase to maximum. This will raise fluid tem-
perature abnormally.
3. Check pressure with steering wheel fully turned to left and right
positions with engine idling at 1,000 rpm.
CAUTION:
Do not hold the steering wheel in a locked position for more
than 15 seconds.
Power steering pump maximum operating pressure:
8,630 - 9,219 kPa
(88 - 94 kg/cm
2, 1,251 - 1,337 psi)
IIf pressure reaches maximum operating pressure, system is
OK.
IIf pressure increases above maximum operating pressure,
check power steering pump flow control valve. Refer to ST-28.
4. If power steering pressure is below the maximum operating
pressure, slowly close shut-off valve and check pressure
again.
CAUTION:
Do not close shut-off valve for more than 15 seconds.
IIf pressure increases to maximum operating pressure, gear
should be damaged. Refer to ªRemoval and Installationº,
ST-18.
IIf pressure remains below maximum operating pressure, pump
should be damaged. Refer to ªDisassemblyº, ST-28.
5. After checking hydraulic system, remove Tool and add fluid as
necessary. Then completely bleed air out of system. Refer to
ST-9.
ON-VEHICLE SERVICE
Checking Steering Wheel Turning Force (Cont'd)
ST-10

TRANSFER
SECTION
TF
CONTENTS
PRECAUTIONS...............................................................3
Supplemental Restraint System (SRS)²AIR
BAG²and²SEAT BELT PRE-TENSIONER²...............3
Precautions ..................................................................3
Service Notice..............................................................4
Wiring Diagrams and Trouble Diagnosis .....................4
PREPARATION...............................................................5
Special Service Tools ..................................................5
Commercial Service Tools ...........................................9
ALL-MODE 4WD SYSTEM...........................................10
Cross-sectional View .................................................10
Control System .......................................................... 11
ALL-MODE 4WD TRANSFER BASIC CONTROL........12
HYDRAULIC CONTROL CIRCUITS...........................12
OUTLINE................................................................12
CONTROL SYSTEM DIAGRAM................................13
INDICATIONS OF 4WD WARNING LAMP..................13
Location of Electrical Parts ........................................14
Description of Electrical Parts ...................................15
TRANSFER MOTOR................................................15
WAIT DETECTION SWITCH.....................................15
2-4WD SHIFT SOLENOID VALVE.............................16
LINE PRESSURE SWITCH.......................................16
Circuit Diagram for Quick Pinpoint Check.................17
Wiring Diagram - TF -................................................18
ON BOARD DIAGNOSTIC SYSTEM
DESCRIPTION...............................................................27
Trouble Diagnosis without CONSULT-II ....................27
DESCRIPTION........................................................27
SELF-DIAGNOSTIC PROCEDURE............................28
INDICATIONS OF 4WD WARNING LAMP..................29
Trouble Diagnosis with CONSULT-II .........................30
SELF-DIAGNOSIS...................................................30
SELF-DIAGNOSTIC ITEMS......................................31
DATA MONITOR......................................................33
DATA MONITOR ITEMS...........................................34
REFERENCE VALUE IN DATA MONITOR MODE......36
WORK SUPPORT....................................................38
CLUTCH FORCE RELEASE LIMIT ADJUSTMENT.....39
TROUBLE DIAGNOSIS - INTRODUCTION..................41Introduction ................................................................41
DESCRIPTION........................................................41
DIAGNOSTIC WORKSHEET.....................................41
Work Flow ..................................................................43
HOW TO PERFORM TROUBLE DIAGNOSES FOR
QUICK AND ACCURATE REPAIR
.............................43
TROUBLE DIAGNOSIS - BASIC INSPECTION...........44
Listen to Customer Complaints .................................44
Transfer Fluid Check .................................................44
Road Test...................................................................44
PREPARATION FOR ROAD TEST............................44
1. CHECK BEFORE ENGINE IS STARTED...............45
2. CHECK AT IDLE..................................................47
3. CRUISE TEST.....................................................51
TROUBLE DIAGNOSIS - GENERAL
DESCRIPTION...............................................................54
Transfer Control Unit Terminals and Reference
Value ..........................................................................54
REMOVAL AND INSTALLATION OF TRANSFER
CONTROL UNIT
......................................................54
INSPECTION OF TRANSFER CONTROL UNIT..........54
TRANSFER CONTROL UNIT INSPECTION TABLE....55
VEHICLE SPEED SENSOR (FRONT
REVOLUTION SENSOR)..............................................61
Diagnostic Procedure ................................................61
4WD SOLENOID VALVE...............................................64
Diagnostic Procedure ................................................64
2-4WD SHIFT SOLENOID VALVE AND 4WD
SHIFT SWITCH..............................................................66
Diagnostic Procedure ................................................66
TRANSFER MOTOR AND TRANSFER MOTOR
RELAY...........................................................................70
Diagnostic Procedure ................................................70
TRANSFER FLUID TEMPERATURE SENSOR............73
Diagnostic Procedure ................................................73
ATP SWITCH, WAIT DETECTION SWITCH AND
NEUTRAL-4LO SWITCH...............................................76
Diagnostic Procedure ................................................76
CLUTCH PRESSURE SWITCH....................................80
Diagnostic Procedure ................................................80
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CONTROL SYSTEM DIAGRAMNBTF0007S04
SMT763D
INDICATIONS OF 4WD WARNING LAMPNBTF0007S05
Condition Content 4WD warning lamp
During self-diagnosis Indicates the malfunction position by number of flickers. Flickers at malfunction mode.
Lamp check*Checks the lamp by turning ON during engine starting. After
engine starts, it turns OFF if there are no malfunctions.ON
Malfunction in 4WD system*Turns ON to indicate malfunction. When ignition switch is
turned to ªOFFº or the malfunction is corrected, it turns OFF.ON
When vehicle is driven with different
diameters of front and rear tiresFlickers once every 2 seconds.
Turns OFF when ignition switch is ªOFFº.Flickers once every 2 sec-
onds.
High fluid temperature in transfer
unitWhen fluid temperature is high or fluid temperature sensor
circuit is shorted, it flickers twice every second.
It turns OFF when fluid temperature becomes normal.Flickers twice a second.
Other than above (System is nor-
mal.)Lamp is OFF. OFF
*: When 4WD warning lamp is ON, all the 4WD shift indicator lamps turn OFF.
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ALL-MODE 4WD SYSTEM
Control System (Cont'd)
TF-13

INDICATIONS OF 4WD WARNING LAMPNBTF0011S03
Flickering pattern or flick-
ering conditionMalfunction Check items
1 Front revolution sensor circuit is shorted or open.Revolution sensor (front) circuit,
TF-61.
2 Rear revolution sensor circuit is shorted or open.Revolution sensor (rear) [Refer to
AT-111, ªDTC P0720 Vehicle Speed
Sensor´A/T (Revolution sensor)º.]
3 4WD solenoid valve circuit is shorted or open. 4WD solenoid valve circuit, TF-64.
42-4WD shift solenoid valve circuit is shorted or 2WD switch of
4WD shift switch is shorted.2-4WD shift solenoid valve circuit or
4WD shift switch circuit, TF-66.
5 Transfer motor relay circuit is shorted or open. Transfer motor relay circuit, TF-70.
8Power supply voltage of throttle position sensor is improper. Or
A/D converter of transfer control unit functions improperly.Throttle position sensor (Refer to
AT-176, ªDTC P1705 Throttle Posi-
tion Sensorº.)
9 Transfer fluid temperature sensor circuit is open.Transfer fluid temperature sensor
circuit, TF-73.
10 Neutral-4LO switch circuit is shorted or open. Neutral-4LO switch circuit, TF-76.
112-4WD shift solenoid valve circuit, 2WD switch of 4WD shift
switch circuit or clutch pressure switch circuit is shorted or open.2-4WD shift solenoid valve circuit,
4WD shift switch circuit or clutch
pressure switch circuit, TF-66, 80.
12 Line pressure switch circuit is shorted or open. Line pressure switch circuit, TF-83.
13 Engine speed signal circuit is shorted or open.Engine speed signal (Refer to
AT-116, ªDTC P0725 Engine Speed
Signalº.)
14 Throttle position sensor circuit is shorted or open.Throttle position sensor (Refer to
AT-176, ªDTC P1705 Throttle Posi-
tion Sensorº.)
15 Failure in power supply circuit of transfer control unit. Power supply of transfer control unit
16 4WD shift switch circuit is shorted. 4WD shift switch circuit, TF-66.
17 ABS operation signal circuit is shorted. ABS operation signal circuit, TF-86.
18ATP switch, wait detection switch or neutral-4LO switch circuit is
shorted or open.ATP switch, wait detection switch or
neutral-4LO switch circuit*, TF-76.
19Transfer control device actuator motor is faulty. (Abnormalities
are detected when actuator motor fails to operate while shifting
from ª4Hº to ª4LOº or vice versa.)Actuator motor and motor circuit,
TF-115, 89.
20Transfer control device actuator motor arm position sensing
switch is faulty.Actuator motor arm position sensing
switch and sensing switch circuit,
TF-115, 92.
21Transfer control device actuator circuit is faulty (Abnormalities
are detected when motor relay circuit is open/shorted or relay
monitor circuit is open/shorted.)Actuator motor, actuator motor arm
position sensing switch and their
associated circuits, TF-114, 115 and
94.
Repeats flickering every
2 to 5 sec.Circuits that the self-diagnosis covers have no malfunction. Ð
Repeats flickering every
0.25 sec.IPower supply failure of memory back-up.
IBattery is disconnected for a long time.
IBattery performance is poor.Data erase/display circuit, TF-88.GI
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ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Trouble Diagnosis without CONSULT-II (Cont'd)
TF-29

SMT963D
12. Monitored data are displayed.
DATA MONITOR ITEMSNBTF0012S04q: StandardH: Option
Item [Unit]Monitor item
Remarks
ECU input
signalsMain sig-
nalsItem menu
selection
Revolution sensor-front [km/h (MPH)]qHRevolution sensor installed on T/F
Revolution sensor-rear [km/h (MPH)]qHVehicle speed sensor´A/T
Engine speed [rpm]qH
Throttle position sensor [V]qH
Transfer fluid temperature sensor [V]qH
Battery voltage [V]qH
2WD switch [ON-OFF]qH2WD switch of 4WD shift switch
AUTO switch [ON-OFF]qHAUTO switch of 4WD shift switch
Lock switch [ON-OFF]qH4H switch of 4WD shift switch
4L switch [ON-OFF]qH4LO switch of 4WD shift switch
N position switch TF [ON-OFF]qHN position switch of transfer
Line pressure switch [ON-OFF]qHLine pressure switch
Clutch pressure switch [ON-OFF]qHClutch pressure switch
ATP switch [ON-OFF]qH
N position switch [ON-OFF]qHªNº position on A/T PNP switch
R position switch [ON-OFF]qHªRº position on A/T PNP switch
P position switch [ON-OFF]qHªPº position on A/T PNP switch
Closed throttle position switch
[ON/OFF]qHIdle contact of throttle position switch
ABS operation switch [ON-OFF]qHABS operation switch
Wait detection switch [ON-OFF]qH
Throttle openingqHThrottle opening recognized by transfer control
unit
4WD-modeqH4WD-mode recognized by transfer control unit
(2W, AUTO, 4H & 4LO)
Vehicle speed comp [km/h (MPH)]qHVehicle speed recognized by transfer control
unit
*Control torque [N´m (kg-m, ft-lb)]qHCalculated torque recognized by transfer control
unit
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Trouble Diagnosis with CONSULT-II (Cont'd)
TF-34

REFERENCE VALUE IN DATA MONITOR MODENBTF0012S09
Indicated items
(Screen terms for CONSULT, ªDATA
MONITORº mode)Display Conditions
Throttle position sensor
(THRTL POS SEN)Approx. 0.5 - 4.0V Throttle valve fully closed to fully open
Transfer fluid temperature sensor
(FLUID TEMP SE)Approx. 1.5 - 0.5VTransfer fluid temperature approx. 20 - 80ÉC (68 -
176ÉF)
Closed throttle position switch
(CLOSED THL/SW)ON After engine warm-up, accelerator pedal is released.
OFF After engine warm-up, accelerator pedal is depressed.
ABS operation switch
(ABS OPER SW)OFF ABS is not operating.
ON ABS is operating.
ABS control operation
(ABS CONT OPER)ONABS OPER SW is ªONº. Control operation is accom-
plished in combination with ABS.
OFFABS is not operating. When a message such as
ªimproper ABS operation signalº appears on the display
and ABS OPER SW is ªONº, control operation is not
accomplished in combination with ABS.
2WD position
(2WD SW)ON 4WD shift switch is in ª2WDº.
OFF Except the above condition
Lock position
(LOCK SWITCH)ON 4WD shift switch is in ª4Hº.
OFF Except the above condition
Neutral-4LO switch
(N POSI SW TF)
ATP switch
(ATP SWITCH)
Wait detection switch
(WAIT DETCT SW)4WD shift switch position2WD, AUTO,
4H(N) 4LO
ATP switch OFF ON OFF
Neutral-4LO switch OFF ON
Wait detection switchOFF ON
See Note.
Note: When shifting from ª4LOº to ª2WDº, ªAUTOº, ª4Hº, it turns ON when ªWaitº function
is operating (and it turns OFF when ªWaitº function is canceled).
Transfer motor relay
(MOTOR RELAY)Throttle valve4WD shift
switchA/T selector
leverMotor relay Remarks
Fully closed2WD Ð OFF
AUTO,
4LOP, N OFF
ON for approx. 2 sec. after
shifting to ªPº and ªNº
Others ON
4HP OFF
ON for approx. 2 sec. after
shifting to ªPº
Others ON
Line pressure switch
(LINE PRES SW)OFFThe vehicle has been left at room temperature for 5 min-
utes and more with ignition switch in ªOFFº position.
ONIgnition switch in ªONº, and 4WD shift switch in ªAUTOº
or ª4Hº and A/T selector lever in ªDº.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Trouble Diagnosis with CONSULT-II (Cont'd)
TF-36

Indicated items
(Screen terms for CONSULT, ªDATA
MONITORº mode)Display Conditions
Clutch pressure switch
(CL PRES SW)OFFIgnition switch in ªONº, and 4WD shift switch in ª2WDº.
(ªWaitº function is not operating.)
ONIgnition switch in ªONº, and 4WD shift switch in ªAUTOº
or ª4Hº and A/T selector lever in ªDº. (ªWaitº function is
not operating.)
Control torque
(COMP CL TORQ)0 kg-m
4WD shift switch
(ªWaitº function is not oper-
ating.)In ª2WDº position
39 - 1,079 N´m
(4 - 110 kg-m, 29 - 796 ft-lb)In ªAUTOº position
1,079 N´m
(110 kg-m, 796 ft-lb)In ª4Hº or ª4LOº position
4WD solenoid
(DUTY SOLENOID)4% In ª2WDº position
94 - 4% In ªAUTOº position
4% In ª4Hº or ª4LOº position
2-4WD shift solenoid valve
(2-4WD SOL)OFF
4WD shift switchIn ª2WDº position
ON (ªWaitº function is not oper-
ating.)
In ªAUTOº position
OFF (ªWaitº function is operat-
ing.)
ON (ªWaitº function is not oper-
ating.)
In ª4Hº position
OFF (ªWaitº function is operat-
ing.)
ON In ª4LOº position
Indicated items Display Conditions
Battery voltage Approx. 12V Key switch ªONº and engine at rest
Approx. 13 - 14V During idling
AUTO switch OFF 4WD shift switch in other than ªAUTOº position
ON 4WD shift switch in ªAUTOº position
4L switch OFF 4WD shift switch in other than ª4LOº position
ON 4WD shift switch in ª4LOº position
N position switch OFF A/T selector lever in other than ªNº position
ON A/T selector lever in ªNº position
R position swtich OFF A/T selector lever in other than ªRº position
ON A/T selector lever in ªRº position
P position switch OFF A/T selector lever in other than ªPº position
ON A/T selector lever in ªPº position
Throttle opening 0.0/8 - 8.0/8 Throttle fully closed (0.0/8) or throttle fully open (8.0/8)
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ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Trouble Diagnosis with CONSULT-II (Cont'd)
TF-37

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

5 CHECK INPUT SIGNAL
Without CONSULT-II
1. Start engine.
2. Check voltage between transfer control unit harness connector terminals 38 and 28.
(Measure it in AC range.)
Voltage:
0 km/h (0 MPH): 0V
30 km/h (19 MPH): More than 1V
(Voltage rises gradually in response to vehicle speed.)
SMT774D
OK or NG
OK©GO TO 6.
NG©GO TO 7.
6 PERFORM SELF-DIAGNOSIS AGAIN
After driving for a while, perform self-diagnosis again.
Refer to ªTrouble Diagnosis without CONSULT-IIº, TF-27.
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.
7 CHECK HARNESS CONTINUITY BETWEEN TRANSFER CONTROL UNIT AND FRONT REVOLUTION
SENSOR SUB-HARNESS CONNECTOR
OK or NG
OK©GO TO 6.
NG©Repair or replace sub-harness connector between transfer control unit and front revolu-
tion sensor.
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VEHICLE SPEED SENSOR (FRONT REVOLUTION SENSOR)
Diagnostic Procedure (Cont'd)
TF-63