2001 INFINITI QX4 torque

Component Inspection .............................................131
DTC P0733 IMPROPER SHIFTING TO 3RD GEAR
POSITION....................................................................132
Description ...............................................................132
Wiring Diagram - AT - 3RD......................................135
Diagnostic Procedure ..............................................136
Component Inspection .............................................137
DTC P0734 IMPROPER SHIFTING TO 4TH GEAR
POSITION....................................................................138
Description ...............................................................138
Wiring Diagram - AT - 4TH ......................................142
Diagnostic Procedure ..............................................143
Component Inspection .............................................147
DTC P0740 TORQUE CONVERTER CLUTCH
SOLENOID VALVE......................................................148
Description ...............................................................148
Wiring Diagram - AT - TCV......................................150
Diagnostic Procedure ..............................................151
Component Inspection .............................................152
DTC P0744 IMPROPER LOCK-UP OPERATION......153
Description ...............................................................153
Wiring Diagram - AT - TCCSIG ...............................156
Diagnostic Procedure ..............................................157
Component Inspection .............................................161
DTC P0745 LINE PRESSURE SOLENOID VALVE...162
Description ...............................................................162
Wiring Diagram - AT - LPSV....................................164
Diagnostic Procedure ..............................................165
Component Inspection .............................................167
DTC P0750 SHIFT SOLENOID VALVE A..................168
Description ...............................................................168
Wiring Diagram - AT - SSV/A ..................................169
Diagnostic Procedure ..............................................170
Component Inspection .............................................171
DTC P0755 SHIFT SOLENOID VALVE B..................172
Description ...............................................................172
Wiring Diagram - AT - SSV/B ..................................173
Diagnostic Procedure ..............................................174
Component Inspection .............................................175
DTC P1705 THROTTLE POSITION SENSOR...........176
Description ...............................................................176
Wiring Diagram - AT - TPS ......................................179
Diagnostic Procedure ..............................................180
Component Inspection .............................................184
DTC P1760 OVERRUN CLUTCH SOLENOID
VALVE..........................................................................185
Description ...............................................................185
Wiring Diagram - AT - OVRCSV..............................187
Diagnostic Procedure ..............................................188
Component Inspection .............................................189
DTC BATT/FLUID TEMP SEN (A/T FLUID TEMP
SENSOR CIRCUIT AND TCM POWER SOURCE)....190Description ...............................................................190
Wiring Diagram - AT - BA/FTS ................................192
Diagnostic Procedure ..............................................193
Component Inspection .............................................196
DTC VEHICLE SPEED SENSOR.MTR.......................197
Description ...............................................................197
Wiring Diagram - AT - VSSMTR ..............................199
Diagnostic Procedure ..............................................200
DTC TURBINE REVOLUTION SENSOR....................202
Description ...............................................................202
Wiring Diagram - AT - TRSA/T ................................204
Diagnostic Procedure ..............................................205
Component Inspection .............................................206
DTC A/T COMMUNICATION LINE.............................207
Description ...............................................................207
Wiring Diagram - AT - LAN ......................................209
Diagnostic Procedure ..............................................210
DTC CONTROL UNIT (RAM), CONTROL UNIT
(ROM)........................................................................... 211
Description ............................................................... 211
Diagnostic Procedure ..............................................212
DTC CONTROL UNIT (EEP ROM).............................213
Description ...............................................................213
Diagnostic Procedure ..............................................214
TROUBLE DIAGNOSES FOR SYMPTOMS...............215
Wiring Diagram - AT - NONDTC .............................215
1. O/D OFF Indicator Lamp Does Not Come On....218
2. Engine Cannot Be Started In²P²and²N²
Position ....................................................................221
3. In²P²Position, Vehicle Moves Forward Or
Backward When Pushed .........................................222
4. In²N²Position, Vehicle Moves ...........................223
5. Large Shock.²N²->²R²Position .......................225
6. Vehicle Does Not Creep Backward In²R²
Position ....................................................................227
7. Vehicle Does Not Creep Forward In²D²,²2²
Or²1²Position .........................................................230
8. Vehicle Cannot Be Started From D
1...................233
9. A/T Does Not Shift: D
1-> D2Or Does Not
Kickdown: D
4-> D2..................................................236
10. A/T Does Not Shift: D
2-> D3.............................239
11. A/T Does Not Shift: D
3-> D4.............................242
12. A/T Does Not Perform Lock-up .........................245
13. A/T Does Not Hold Lock-up Condition ..............247
14. Lock-up Is Not Released ...................................249
15. Engine Speed Does Not Return To Idle (Light
Braking D
4-> D3).....................................................250
16. Vehicle Does Not Start From D
1.......................252
17. A/T Does Not Shift: D
4-> D3, When
Overdrive Control Switch²ON²->²OFF²...............253
18. A/T Does Not Shift: D
3-> 22, When Selector
Lever²D²->²2²Position.........................................254
CONTENTS(Cont'd)
AT-2

IBefore assembly, apply a coat of recommended ATF to all
parts. Apply petroleum jelly to protect O-rings and seals, or
hold bearings and washers in place during assembly. Do not
use grease.
IExtreme care should be taken to avoid damage to O-rings,
seals and gaskets when assembling.
IReplace ATF cooler if excessive foreign material is found in oil
pan or clogging strainer. Refer to ªATF COOLER SERVICEº,
AT-9.
IAfter overhaul, refill the transmission with new ATF.
IWhen the A/T drain plug is removed, only some of the fluid is
drained. Old A/T fluid will remain in torque converter and ATF
cooling system.
Always follow the procedures when changing A/T fluid. Refer
to MA-21, ªChanging A/T Fluidº.
Service Notice or PrecautionsNBAT0004FAIL-SAFENBAT0004S01The TCM has an electronic Fail-Safe (limp home mode). This allows the vehicle to be driven even if a major
electrical input/output device circuit is damaged.
Under Fail-Safe, the vehicle always runs in third gear, even with a shift lever position of ª1º, ª2º or ªDº. The
customer may complain of sluggish or poor acceleration.
When the ignition key is turned ªONº following Fail-Safe operation, O/D OFF indicator lamp blinks for about
8 seconds. (For ªTCM SELF-DIAGNOSTIC PROCEDURE (No Tools)º, refer to AT-46.)
Fail-Safe may occur without electrical circuit damage if the vehicle is driven under extreme conditions (such
as excessive wheel spin followed by sudden braking). To recover normal shift pattern, turn the ignition key
ªOFFº for 5 seconds, then ªONº.
The blinking of the O/D OFF indicator lamp for about 8 seconds will appear only once and be cleared. The
customer may resume normal driving conditions.
Always follow the ªWORK FLOWº (Refer to AT-57).
The SELF-DIAGNOSIS results will be as follows:
The first SELF-DIAGNOSIS will indicate damage to the vehicle speed sensor or the revolution sensor.
During the next SELF-DIAGNOSIS, performed after checking the sensor, no damages will be indicated.
TORQUE CONVERTER SERVICENBAT0004S04The torque converter should be replaced under any of the following conditions:
IExternal leaks in the hub weld area.
IConverter hub is scored or damaged.
IConverter pilot is broken, damaged or fits poorly into crankshaft.
ISteel particles are found after flushing the cooler and cooler lines.
IPump is damaged or steel particles are found in the converter.
IVehicle has TCC shudder and/or no TCC apply. Replace only after all hydraulic and electrical diagnoses
have been made. (Converter clutch material may be glazed.)
IConverter is contaminated with engine coolant containing antifreeze.
IInternal failure of stator roller clutch.
IHeavy clutch debris due to overheating (blue converter).
ISteel particles or clutch lining material found in fluid filter or on magnet when no internal parts in unit are
worn or damaged Ð indicates that lining material came from converter.
The torque converter should not be replaced if:
IThe fluid has an odor, is discolored, and there is no evidence of metal or clutch facing particles.
PRECAUTIONS
Precautions (Cont'd)
AT-8

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

Special Service ToolsNBAT0006The actual shapes of Kent-Moore tools may differ from those of special service tools illustrated here.
Tool number
(Kent-Moore No.)
Tool nameDescription
ST2505S001
(J34301-C)
Oil pressure gauge set
1 ST25051001
(Ð)
Oil pressure gauge
2 ST25052000
(Ð)
Hose
3 ST25053000
(Ð)
Joint pipe
4 ST25054000
(Ð)
Adapter
5 ST25055000
(Ð)
Adapter
NT097
Measuring line pressure
ST07870000
(J37068)
Transmission case stand
NT421
Disassembling and assembling A/T
a: 182 mm (7.17 in)
b: 282 mm (11.10 in)
c: 230 mm (9.06 in)
d: 100 mm (3.94 in)
KV31102100
(J37065)
Torque converter one-
way clutch check tool
NT098
Checking one-way clutch in torque converter
ST25850000
(J25721-A)
Sliding hammer
NT422
Removing oil pump assembly
a: 179 mm (7.05 in)
b: 70 mm (2.76 in)
c: 40 mm (1.57 in) dia.
d: M12 x 1.75P
KV31102400
(J34285 and J34285-87)
Clutch spring compres-
sor
NT423
Removing and installing clutch return springs
a: 320 mm (12.60 in)
b: 174 mm (6.85 in)
PREPARATION
Special Service Tools
AT-10

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

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

TCM FUNCTION=NBAT0013S03The function of the TCM is to:
IReceive input signals sent from various switches and sensors.
IDetermine required line pressure, shifting point, lock-up operation, and engine brake operation.
ISend required output signals to the respective solenoids.
INPUT/OUTPUT SIGNAL OF TCMNBAT0013S04
Sensors and solenoid valves Function
InputPNP switch Detects select lever position and sends a signal to TCM.
Throttle position sensor Detects throttle valve position and sends a signal to TCM.
Closed throttle position switch Detects throttle valve's fully-closed position and sends a signal to TCM.
Wide open throttle position switchDetects a throttle valve position of greater than 1/2 of full throttle and sends
a signal to TCM.
Engine speed signal From ECM.
A/T fluid temperature sensor Detects transmission fluid temperature and sends a signal to TCM.
Revolution sensor Detects output shaft rpm and sends a signal to TCM.
Vehicle speed sensorUsed as an auxiliary vehicle speed sensor. Sends a signal when revolution
sensor (installed on transmission) malfunctions.
Overdrive control switchSends a signal, which prohibits a shift to ªD
4º (overdrive) position, to the
TCM.
ASCD control unitSends the cruise signal and ªD
4º (overdrive) cancellation signal from ASCD
control unit to TCM.
Turbine revolution sensor Sends an input shaft revolution signal.
Stop lamp switch Sends the lock-up release signal to the TCM at time of D
4(lock-up).
OutputShift solenoid valve A/BSelects shifting point suited to driving conditions in relation to a signal sent
from TCM.
Line pressure solenoid valveRegulates (or decreases) line pressure suited to driving conditions in rela-
tion to a signal sent from TCM.
Torque converter clutch solenoid
valveRegulates (or decreases) lock-up pressure suited to driving conditions in
relation to a signal sent from TCM.
Overrun clutch solenoid valveControls an ªengine brakeº effect suited to driving conditions in relation to a
signal sent from TCM.
O/D OFF indicator lamp Shows TCM faults, when A/T control components malfunction.
Control MechanismNBAT0180LINE PRESSURE CONTROLNBAT0180S01TCM has the various line pressure control characteristics to meet
the driving conditions.
An ON-OFF duty signal is sent to the line pressure solenoid valve
based on TCM characteristics.
Hydraulic pressure on the clutch and brake is electronically con-
trolled through the line pressure solenoid valve to accommodate
engine torque. This results in smooth shift operation.
OVERALL SYSTEM
Control System (Cont'd)
AT-26

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