2001 INFINITI QX4 automatic transmission

AUTOMATIC TRANSMISSION
SECTION
AT
CONTENTS
TROUBLE DIAGNOSIS - INDEX....................................4
Alphabetical & P No. Index for DTC ...........................4
PRECAUTIONS...............................................................6
Precautions for Supplemental Restraint System
(SRS)²AIR BAG²and²SEAT BELT
PRE-TENSIONER²......................................................6
Precautions for On Board Diagnostic (OBD)
System of A/T and Engine...........................................6
Precautions ..................................................................6
Service Notice or Precautions .....................................8
Wiring Diagrams and Trouble Diagnosis .....................9
PREPARATION.............................................................10
Special Service Tools ................................................10
OVERALL SYSTEM......................................................12
A/T Electrical Parts Location .....................................12
Circuit Diagram ..........................................................13
Cross-sectional View .................................................14
Hydraulic Control Circuit ............................................15
Shift Mechanism ........................................................16
Control System ..........................................................25
Control Mechanism ....................................................26
Control Valve .............................................................31
ON BOARD DIAGNOSTIC SYSTEM
DESCRIPTION...............................................................33
Introduction ................................................................33
OBD-II Function for A/T System ................................33
One or Two Trip Detection Logic of OBD-II ..............33
OBD-II Diagnostic Trouble Code (DTC) ....................33
Malfunction Indicator Lamp (MIL) ..............................37
CONSULT-II ...............................................................37
Diagnostic Procedure Without CONSULT-II ..............46
TROUBLE DIAGNOSIS - INTRODUCTION..................53
Introduction ................................................................53
Work Flow ..................................................................57
TROUBLE DIAGNOSIS - BASIC INSPECTION...........59
A/T Fluid Check .........................................................59
Stall Test ....................................................................59
Line Pressure Test .....................................................62
Road Test...................................................................63TROUBLE DIAGNOSIS - GENERAL
DESCRIPTION...............................................................81
Symptom Chart ..........................................................81
TCM Terminals and Reference Value........................92
TROUBLE DIAGNOSIS FOR POWER SUPPLY..........96
Wiring Diagram - AT - MAIN ......................................96
Diagnostic Procedure ................................................97
DTC P0705 PARK/NEUTRAL POSITION SWITCH.....99
Description .................................................................99
Wiring Diagram - AT - PNP/SW...............................101
Diagnostic Procedure ..............................................102
Component Inspection .............................................103
DTC P0710 A/T FLUID TEMPERATURE SENSOR
CIRCUIT.......................................................................105
Description ...............................................................105
Wiring Diagram - AT - FTS ......................................107
Diagnostic Procedure ..............................................108
Component Inspection ............................................. 110
DTC P0720 VEHICLE SPEED SENSOR.A/T
(REVOLUTION SENSOR)........................................... 111
Description ............................................................... 111
Wiring Diagram - AT - VSSA/T ................................ 113
Diagnostic Procedure .............................................. 114
Component Inspection ............................................. 115
DTC P0725 ENGINE SPEED SIGNAL....................... 116
Description ............................................................... 116
Wiring Diagram - AT - ENGSS ................................ 117
Diagnostic Procedure .............................................. 118
DTC P0731 IMPROPER SHIFTING TO 1ST GEAR
POSITION....................................................................120
Description ...............................................................120
Wiring Diagram - AT - 1ST ......................................123
Diagnostic Procedure ..............................................124
Component Inspection .............................................125
DTC P0732 IMPROPER SHIFTING TO 2ND GEAR
POSITION....................................................................126
Description ...............................................................126
Wiring Diagram - AT - 2ND......................................129
Diagnostic Procedure ..............................................130
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IThe threads in one or more of the converter bolt holes are damaged.
ITransmission failure did not display evidence of damaged or worn internal parts, steel particles or clutch
plate lining material in unit and inside the fluid filter.
IVehicle has been exposed to high mileage (only). The exception may be where the torque converter clutch
dampener plate lining has seen excess wear by vehicles operated in heavy and/or constant traffic, such
as taxi, delivery or police use.
ATF COOLER SERVICENBAT0004S02Replace ATF cooler if excessive foreign material is found in oil pan or clogging strainer.
Replace radiator lower tank (which includes ATF cooler) with a new one and flush cooler line using cleaning
solvent and compressed air. Refer to LC-19, ªREMOVAL AND INSTALLATIONº.
OBD-II SELF-DIAGNOSISNBAT0004S03IA/T self-diagnosis is performed by the TCM in combination with the ECM. The results can be read through
the blinking pattern of the O/D OFF indicator or the malfunction indicator lamp (MIL). Refer to the table on
AT-38 for the indicator used to display each self-diagnostic result.
IThe self-diagnostic results indicated by the MIL are automatically stored in both the ECM and TCM
memories.
Always perform the procedure ªHOW TO ERASE DTCº on AT-35 to complete the repair and avoid
unnecessary blinking of the MIL.
IThe following self-diagnostic items can be detected using ECM self-diagnostic results mode* only when
the O/D OFF indicator lamp does not indicate any malfunctions.
þ PNP switch
þ A/T 1st, 2nd, 3rd, or 4th gear function
þ A/T TCC S/V function (lock-up)
*: For details of OBD-II, refer to EC-59, ªIntroductionº.
ICertain systems and components, especially those related to OBD, may use the new style slide-
locking type harness connector. For description and how to disconnect, refer to EL-5, ªDescrip-
tionº.
Wiring Diagrams and Trouble DiagnosisNBAT0005When you read wiring diagrams, refer to the following:
IGI-11, ªHOW TO READ WIRING DIAGRAMSº.
IEL-9, ªPOWER SUPPLY ROUTINGº for power distribution circuit.
When you perform trouble diagnosis, refer to the following:
IGI-35, ªHOW TO FOLLOW TEST GROUP IN TROUBLE DIAGNOSISº.
IGI-24, ªHOW TO PERFORM EFFICIENT DIAGNOSIS FOR AN ELECTRICAL INCIDENTº.
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PRECAUTIONS
Service Notice or Precautions (Cont'd)
AT-9

Shift MechanismNBAT0012The automatic transmission uses compact, dual planetary gear systems to improve power-transmission
efficiency, simplify construction and reduce weight.
It also employs an optimum shift control and superwide gear ratios. They improve starting performance and
acceleration during medium and high-speed operation.
Two one-way clutches are also employed: one is used for the forward clutch and the other for the low clutch.
These one-way clutches, combined with four accumulators, reduce shifting shock to a minimum.
CONSTRUCTIONNBAT0012S01
SAT509I
1. Torque converter clutch piston
2. Torque converter
3. Oil pump
4. Input shaft
5. Brake band
6. Reverse clutch
7. High clutch
8. Front pinion gear9. Front sun gear
10. Front internal gear
11. Front planetary carrier
12. Rear sun gear
13. Rear pinion gear
14. Rear internal gear
15. Rear planetary carrier
16. Forward clutch17. Forward one-way clutch
18. Overrun clutch
19. Low one-way clutch
20. Low & reverse brake
21. Parking pawl
22. Parking gear
23. Output shaft
FUNCTION OF CLUTCH AND BRAKENBAT0012S02
Clutch and brake components Abbr. Function
Reverse clutch6R/C To transmit input power to front sun gear9.
High clutch7H/C To transmit input power to front planetary carrier11.
Forward clutch16F/C To connect front planetary carrier11with forward one-way
clutch17.
Overrun clutch18O/C To connect front planetary carrier11with rear internal gear14.
Brake band5B/B To lock front sun gear9.
Forward one-way clutch17F/O.C When forward clutch16is engaged, to stop rear internal gear
14from rotating in opposite direction against engine revolution.
Low one-way clutch19L/O.C To stop front planetary carrier11from rotating in opposite direc-
tion against engine revolution.
Low & reverse brake20L & R/B To lock front planetary carrier11.
OVERALL SYSTEM
Shift Mechanism
AT-16

CLUTCH AND BAND CHARTNBAT0012S03
Shift positionReverse
clutchHigh
clutchFor-
ward
clutchOver-
run
clutchBand servoFor-
ward
one
-way
clutchLow
one-
way
clutchLow &
reverse
brakeLock-up Remarks
2nd
apply3rd
release4th
apply
PPARK
POSITION
RqqREVERSE
POSITION
NNEUTRAL
POSITION
D*41stq*1D B B
Automatic
shift
1k2k3
k4 2ndq*1AqB
3rdqq*1A *2C C B *5q
4thqC *3C Cqq
21stqDBBAutomatic
shift
1k2 2ndq*1AqB
11stqqBqLocks (held
stationary) in
1st speed
1g2 2ndqqqB
*1: Operates when overdrive control switch is being set in ªOFFº position.
*2: Oil pressure is applied to both 2nd ªapplyº side and 3rd ªreleaseº side of band servo piston. However, brake band does not contract
because oil pressure area on the ªreleaseº side is greater than that on the ªapplyº side.
*3: Oil pressure is applied to 4th ªapplyº side in condition *2 above, and brake band contracts.
*4: A/T will not shift to 4th when overdrive control switch is set in ªOFFº position.
*5: Operates when overdrive control switch is ªOFFº.
q: Operates.
A: Operates when throttle opening is less than 3/16, activating engine brake.
B: Operates during ªprogressiveº acceleration.
C: Operates but does not affect power transmission.
D: Operates when throttle opening is less than 3/16, but does not affect engine brake.
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OVERALL SYSTEM
Shift Mechanism (Cont'd)
AT-17

Control System=NBAT0013OUTLINENBAT0013S01The automatic transmission senses vehicle operating conditions through various sensors. It always controls
the optimum shift position and reduces shifting and lock-up shocks.
SENSORS
ETCM
EACTUATORS
PNP switch
Throttle position sensor
Closed throttle position switch
Wide open throttle position switch
Engine speed signal
A/T fluid temperature sensor
Revolution sensor
Vehicle speed sensor
Overdrive control switch
ASCD control unit
Stop lamp switch
Turbine revolution sensorShift control
Line pressure control
Lock-up control
Overrun clutch control
Timing control
Fail-safe control
Self-diagnosis
CONSULT-II communication
line
Duet-EU controlShift solenoid valve A
Shift solenoid valve B
Overrun clutch solenoid valve
Torque converter clutch sole-
noid valve
Line pressure solenoid valve
O/D OFF indicator lamp
T/F control unit
CONTROL SYSTEMNBAT0013S02
SAT125K
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OVERALL SYSTEM
Control System
AT-25

SAT003J
Normal ControlNBAT0180S0101The line pressure to throttle opening characteristics is set for suit-
able clutch operation.
SAT004J
Back-up Control (Engine brake)NBAT0180S0102If the selector lever is shifted to ª2º position while driving in D4(OD)
or D
3, great driving force is applied to the clutch inside the trans-
mission. Clutch operating pressure (line pressure) must be
increased to deal with this driving force.
SAT005J
During Shift ChangeNBAT0180S0103The line pressure is temporarily reduced corresponding to a
change in engine torque when shifting gears (that is, when the shift
solenoid valve is switched for clutch operation) to reduce shifting
shock.
At Low Fluid TemperatureNBAT0180S0104IFluid viscosity and frictional characteristics of the clutch facing
change with fluid temperature. Clutch engaging or band-con-
tacting pressure is compensated for, according to fluid
temperature, to stabilize shifting quality.
SAT006J
IThe line pressure is reduced below 60ÉC (140ÉF) to prevent
shifting shock due to low viscosity of automatic transmission
fluid when temperature is low.
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OVERALL SYSTEM
Control Mechanism (Cont'd)
AT-27

Valve name Function
Shift valve A Simultaneously switches three oil circuits using output pressure of shift solenoid valve
A to meet driving conditions (vehicle speed, throttle opening, etc.).
Provides automatic downshifting and up-shifting (1st,2nd,3rd,4th gears/4th
,3rd,2nd,1st gears) in combination with shift valve B.
Shift valve B Simultaneously switches three oil circuits using output pressure of shift solenoid valve
B in relation to driving conditions (vehicle speed, throttle opening, etc.).
Provides automatic downshifting and up-shifting (1st,2nd,3rd,4th gears/4th
,3rd,2nd,1st gears) in combination with shift valve A.
Shuttle shift valve S Switches hydraulic circuits to provide 3-2 timing control and overrun clutch control in
relation to the throttle opening.
Inactivates the overrun clutch to prevent interlocking in 4th gear when the throttle is
wide open.
Overrun clutch control valve Switches hydraulic circuits to prevent engagement of the overrun clutch simulta-
neously with application of the brake band in 4th gear. (Interlocking occurs if the
overrun clutch engages during D
4gear operation.)
4-2 relay valve Memorizes that the transmission is in 4th gear. Prevents the transmission from down-
shifting from 4th gear to 3rd and then to 2nd in combination with 4-2 sequence valve
and shift valves A and B when downshifting from 4th to 2nd gear.
4-2 sequence valve Prevents band servo pressure from draining before high clutch operating pressure
and band servo releasing pressure drain (from the same circuit) during downshifting
from 4th to 2nd gear.
Servo charger valve An accumulator and a one-way orifice are used in the 2nd gear band servo oil circuit
to dampen shifting shock when shifting from 1st to 2nd gear.
To maintain adequate flow rate when downshifting from 4th or 3rd gear to 2nd gear,
the servo charger valve directs 2nd gear band servo hydraulic pressure to the circuit
without going through the one-way orifice when downshifting from 3rd or a higher
gear.
3-2 timing valve Prevents a late operation of the brake band when shifting selector lever from ªDº to
ª1º or ª2º position while driving in D
3.
ª1º reducing valve Reduces low & reverse brake pressure to dampen engine-brake shock when down-
shifting from the ª1º position 2nd gear to 1st gear.
Overrun clutch reducing valve Reduces oil pressure directed to the overrun clutch and prevents engine-brake shock.
In ª1º and ª2º positions, line pressure acts on the overrun clutch reducing valve to
increase the pressure-regulating point, with resultant engine brake capability.
Torque converter relief valve Prevents an excessive rise in torque converter pressure.
Torque converter clutch control valve,
torque converter clutch control plug and
torque converter clutch control sleeveActivate or inactivate the lock-up function.
Also provide smooth lock-up through transient application and release of the lock-up
system.
Shuttle shift valve D Switches hydraulic circuits so that output pressure of the torque converter clutch sole-
noid valve acts on the lock-up valve in the ªDº position of 2nd, 3rd and 4th gears. (In
the ªDº position 1st gear, lock-up is inhibited.)
ILock-up control is not affected in ªDº position 2nd, 3rd or 4th gears, unless output
pressure of the torque converter clutch solenoid valve is generated by a signal
from the control unit.
OVERALL SYSTEM
Control Valve (Cont'd)
AT-32

SAT136K
DescriptionNBAT0224The turbine revolution sensor detects input shaft rpm (revolutions
per minute). It is located on the input side of the automatic trans-
mission. The vehicle speed sensor A/T (Revolution sensor) is
located on the output side of the automatic transmission. With the
two sensors, input and output shaft rpms are accurately detected.
The result is optimal shift timing during deceleration and improved
shifting.
TCM TERMINALS AND REFERENCE VALUENBAT0224S01Remarks: Specification data are reference values.
Terminal
No.Wire color Item ConditionJudgement
standard
(Approx.)
38 WTurbine revolution
sensor
(Measure in AC
range)
When engine is running at 1,000 rpm1.2V
Voltage rises
gradually in
response to
engine speed.
42 BThrottle position
sensor (Ground)
Ð0V
ON BOARD DIAGNOSIS LOGICNBAT0224S02
Diagnostic trouble code Malfunction is detected when ... Check item (Possible cause)
: TURBINE REV
TCM does not receive the proper voltage
signal from the sensor.IHarness or connectors
(The sensor circuit is open or shorted.)
ITurbine revolution sensor
: 10th judgement flicker
DTC TURBINE REVOLUTION SENSOR
Description
AT-202