Electrical INFINITI QX4 2001 Factory Service Manual

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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Precautions for Supplemental Restraint System
(SRS) ªAIR BAGº and ªSEAT BELT
PRE-TENSIONERº
NBAT0001The supplemental Restraint System such as ªAIR BAGº and ªSEAT BELT PRE-TENSIONERº used along with
a seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain types of
collision. The SRS system composition which is available to INFINITI QX4 is as follows:
IFor a frontal collision
The Supplemental Restraint System consists of driver air bag module (located in the center of the steer-
ing wheel), front passenger air bag module (located on the instrument panel on passenger side), seat belt
pre-tensioners, a diagnosis sensor unit, warning lamp, wiring harness and spiral cable.
IFor a side collision
The Supplemental Restraint System consists of front side air bag module (located in the outer side of front
seat), satellite sensor, diagnosis sensor unit (one of components of air bags for a frontal collision), wiring
harness, warning lamp (one of components of air bags for a frontal collision).
Information necessary to service the system safely is included in theRS sectionof this Service Manual.
WARNING:
ITo avoid rendering the SRS inoperative, which could increase the risk of personal injury or death
in the event of a collision which would result in air bag inflation, all maintenance must be performed
by an authorized INFINITI dealer.
IImproper maintenance, including incorrect removal and installation of the SRS, can lead to per-
sonal injury caused by unintentional activation of the system. For removal of Spiral Cable and Air
Bag Module, see the RS section.
IDo not use electrical test equipment on any circuit related to the SRS unless instructed to in this
Service Manual. Spiral cable and wiring harnesses covered with yellow insulation tape either just
before the harness connectors or for the complete harness are related to the SRS.
Precautions for On Board Diagnostic (OBD)
System of A/T and Engine
NBAT0002The ECM has an on board diagnostic system. It will light up the malfunction indicator lamp (MIL) to warn the
driver of a malfunction causing emission deterioration.
CAUTION:
IBe sure to turn the ignition switch ªOFFº and disconnect the negative battery terminal before any
repair or inspection work. The open/short circuit of related switches, sensors, solenoid valves, etc.
will cause the MIL to light up.
IBe sure to connect and lock the connectors securely after work. A loose (unlocked) connector will
cause the MIL to light up due to an open circuit. (Be sure the connector is free from water, grease,
dirt, bent terminals, etc.)
IBe sure to route and secure the harnesses properly after work. Interference of the harness with a
bracket, etc. may cause the MIL to light up due to a short circuit.
IBe sure to connect rubber tubes properly after work. A misconnected or disconnected rubber tube
may cause the MIL to light up due to a malfunction of the EGR system or fuel injection system,
etc.
IBe sure to erase the unnecessary malfunction information (repairs completed) from the TCM and
ECM before returning the vehicle to the customer.
SEF289H
PrecautionsNBAT0003IBefore connecting or disconnecting the TCM harness
connector, turn ignition switch ªOFFº and disconnect
negative battery terminal. Failure to do so may damage
the TCM. Because battery voltage is applied to TCM even
if ignition switch is turned ªOFFº.
PRECAUTIONS
Precautions for Supplemental Restraint System (SRS) ªAIR BAGº and ªSEAT BELT PRE-TENSIONERº
AT-6

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

A/T Electrical Parts LocationNBAT0007
SAT124K
OVERALL SYSTEM
A/T Electrical Parts Location
AT-12

SAT007J
ILine pressure is increased to a maximum irrespective of the
throttle opening when fluid temperature drops to þ10ÉC (14ÉF).
This pressure rise is adopted to prevent a delay in clutch and
brake operation due to extreme drop of fluid viscosity at low
temperature.
SHIFT CONTROLNBAT0180S02The shift is regulated entirely by electronic control to accommodate
vehicle speed and varying engine operations. This is accomplished
by electrical signals transmitted by the revolution sensor and
throttle position sensor. This results in improved acceleration per-
formance and fuel economy.
SAT008J
Control of Shift Solenoid Valves A and BNBAT0180S0201The TCM activates shift solenoid valves A and B according to sig-
nals from the throttle position sensor and revolution sensor to
select the optimum gear position on the basis of the shift schedule
memorized in the TCM.
The shift solenoid valve performs simple ON-OFF operation. When
set to ªONº, the drain circuit closes and pilot pressure is applied to
the shift valve.
[Relation between shift solenoid valves A and B and gear positions]
Shift solenoid valveGear position
D
1,21,11D2,22,12D3D4(OD) N-P
A ON (Closed) OFF (Open) OFF (Open) ON (Closed) ON (Closed)
B ON (Closed) ON (Closed) OFF (Open) OFF (Open) ON (Closed)
Control of Shift Valves A and BNBAT0180S0202
SAT047J
OVERALL SYSTEM
Control Mechanism (Cont'd)
AT-28

SAT964I
Malfunction Indicator Lamp (MIL)=NBAT0183The MIL is located on the instrument panel.
1. The MIL will light up when the ignition switch is turned ON
without the engine running. This is a bulb check.
IIf the MIL does not light up, refer to EL-114, ªSchematicº.
(Or refer to EC-648, ªWiring Diagramº.)
2. When the engine is started, the MIL should go off.
If the MIL remains on, the on board diagnostic system has
detected an engine system malfunction. For detail, refer to
EC-59, ªIntroductionº.
CONSULT-IINBAT0184After performing ªSELF-DIAGNOSTIC PROCEDURE (WITH CON-
SULT-II)º (AT-37), place check marks for results on the ªDIAGNOS-
TIC WORKSHEETº, AT-55. Reference pages are provided follow-
ing the items.
NOTICE:
1) The CONSULT-II electrically displays shift timing and lock-up
timing (that is, operation timing of each solenoid).
Check for time difference between actual shift timing and the
CONSULT-II display. If the difference is noticeable, mechani-
cal parts (except solenoids, sensors, etc.) may be malfunction-
ing. Check mechanical parts using applicable diagnostic pro-
cedures.
2) Shift schedule (which implies gear position) displayed on
CONSULT-II and that indicated in Service Manual may differ
slightly. This occurs because of the following reasons:
IActual shift schedule has more or less tolerance or allowance,
IShift schedule indicated in Service Manual refers to the point
where shifts start, and
IGear position displayed on CONSULT-II indicates the point
where shifts are completed.
3) Shift solenoid valve ªAº or ªBº is displayed on CONSULT-II at
the start of shifting. Gear position is displayed upon completion
of shifting (which is computed by TCM).
4) Additional CONSULT-II information can be found in the Opera-
tion Manual supplied with the CONSULT-II unit.
SAT014K
SELF-DIAGNOSTIC PROCEDURE (WITH CONSULT-II)NBAT0184S011. Turn on CONSULT-II and touch ªENGINEº for OBD-II detected
items or touch ªA/Tº for TCM self-diagnosis.
If A/T is not displayed, check TCM power supply and ground
circuit. Refer to AT-92. If result is NG, refer to EL-9, ªSche-
maticº.
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ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Malfunction Indicator Lamp (MIL)
AT-37

SAT987J
2. Touch ªSELF-DIAG RESULTSº.
Display shows malfunction experienced since the last erasing
operation.
CONSULT-II performs REAL-TIME SELF-DIAGNOSIS.
Also, any malfunction detected while in this mode will be dis-
played at real time.
SELF-DIAGNOSTIC RESULT TEST MODENBAT0184S02
Detected items
(Screen terms for CONSULT-II, ªSELF-DIAG
RESULTSº test mode)
Malfunction is detected when ...TCM self-diagnosis OBD-II (DTC)
Available by
O/D OFF
indicator lamp or
ªA/Tº on CONSULT-IIAvailable by
malfunction
indicator lamp*2,
ªENGINEº on CON-
SULT-II or GST ªA/Tº ªENGINEº
PNP switch circuitITCM does not receive the cor-
rect voltage signal (based on
the gear position) from the
switch.Ð P0705
ÐPNP SW/CIRC
Revolution sensorITCM does not receive the
proper voltage signal from the
sensor.X P0720
VHCL SPEED
SEN´A/TVEH SPD SEN/CIR
AT
Vehicle speed sensor (Meter)ITCM does not receive the
proper voltage signal from the
sensor.XÐ
VHCL SPEED
SEN´MTRÐ
A/T 1st gear functionIA/T cannot be shifted to the 1st
gear position even if electrical
circuit is good.Ð P0731*1
ÐA/T 1ST GR FNCTN
A/T 2nd gear functionIA/T cannot be shifted to the 2nd
gear position even if electrical
circuit is good.Ð P0732*1
ÐA/T 2ND GR FNCTN
A/T 3rd gear functionIA/T cannot be shifted to the 3rd
gear position even if electrical
circuit is good.Ð P0733*1
ÐA/T 3RD GR FNCTN
A/T 4th gear functionIA/T cannot be shifted to the 4th
gear position even if electrical
circuit is good.Ð P0734*1
ÐA/T 4TH GR FNCTN
A/T TCC S/V function (lock-up)IA/T cannot perform lock-up
even if electrical circuit is good.Ð P0744*1
Ð A/T TCC S/V FNCTN
Shift solenoid valve AITCM detects an improper volt-
age drop when it tries to operate
the solenoid valve.X P0750
SHIFT SOLENOID/V
ASFT SOL A/CIRC
Shift solenoid valve BITCM detects an improper volt-
age drop when it tries to operate
the solenoid valve.X P0755
SHIFT SOLENOID/V
BSFT SOL B/CIRC
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
CONSULT-II (Cont'd)
AT-38

DescriptionNBAT0039IThis is an OBD-II self-diagnostic item and not available in TCM
self-diagnosis.
IThis malfunction will not be detected while the O/D OFF indi-
cator lamp is indicating another self-diagnosis malfunction.
IThis malfunction is detected when the A/T does not shift into
first gear position as instructed by the TCM. This is not caused
by electrical malfunction (circuits open or shorted) but by
mechanical malfunction such as control valve sticking,
improper solenoid valve operation, etc.
Gear position1234
Shift solenoid valve A ON (Closed) OFF (Open) OFF (Open) ON (Closed)
Shift solenoid valve B ON (Closed) ON (Closed) OFF (Open) OFF (Open)
TCM TERMINALS AND REFERENCE VALUENBAT0039S02Remarks: Specification data are reference values.
Terminal
No.Wire color Item ConditionJudgement
standard
(Approx.)
11 L/WShift solenoid
valve A
When shift solenoid valve A operates.
(When driving in ªD
1ºorªD4º.)Battery volt-
age
When shift solenoid valve A does not operate.
(When driving in ªD
2ºorªD3º.)0V
12 L/RShift solenoid
valve BWhen shift solenoid valve B operates.
(When driving in ªD
1ºorªD2º.)Battery volt-
age
When shift solenoid valve B does not operate.
(When driving in ªD
3ºorªD4º.)0V
ON BOARD DIAGNOSIS LOGICNBAT0039S03This diagnosis monitors actual gear position by checking the torque
converter slip ratio calculated by TCM as follows:
Torque converter slip ratio = A x C/B
A: Output shaft revolution signal from revolution sensor
B: Engine speed signal from ECM
C: Gear ratio determined as gear position which TCM supposes
If the actual gear position is higher than the position (1st) supposed
by TCM, the slip ratio will be more than normal. In case the ratio
exceeds the specified value, TCM judges this diagnosis malfunc-
tion.
This malfunction will be caused when either shift solenoid valve A
is stuck open or shift solenoid valve B is stuck open.
Gear position supposed by TCM1234
In case of gear position with no malfunctions1234
In case of gear position with shift solenoid valve A stuck open 2* 2 3 3
In case of gear position with shift solenoid valve B stuck open 4* 3 3 4
*: P0731 is detected.
Diagnostic trouble code Malfunction is detected when ... Check item (Possible cause)
: A/T 1ST GR FNCTN
A/T cannot be shifted to the 1st gear
position even if electrical circuit is good.IShift solenoid valve A
IShift solenoid valve B
IEach clutch
IHydraulic control circuit
: P0731
DTC P0731 IMPROPER SHIFTING TO 1ST GEAR POSITION
Description
AT-120

DescriptionNBAT0042IThis is an OBD-II self-diagnostic item and not available in TCM
self-diagnosis.
IThis malfunction will not be detected while the O/D OFF indi-
cator lamp is indicating another self-diagnosis malfunction.
IThis malfunction is detected when the A/T does not shift into
second gear position as instructed by the TCM. This is not
caused by electrical malfunction (circuits open or shorted) but
by mechanical malfunction such as control valve sticking,
improper solenoid valve operation, etc.
Gear position1234
Shift solenoid valve A ON (Closed) OFF (Open) OFF (Open) ON (Closed)
Shift solenoid valve B ON (Closed) ON (Closed) OFF (Open) OFF (Open)
TCM TERMINALS AND REFERENCE VALUENBAT0042S02Remarks: Specification data are reference values.
Terminal
No.Wire color Item ConditionJudgement
standard
(Approx.)
12 L/RShift solenoid
valve B
When shift solenoid valve B operates.
(When driving in ªD
1ºorªD2º.)Battery volt-
age
When shift solenoid valve B does not operate.
(When driving in ªD
3ºorªD4º.)0V
ON BOARD DIAGNOSIS LOGICNBAT0042S03This diagnosis monitors actual gear position by checking the torque
converter slip ratio calculated by TCM as follows:
Torque converter slip ratio = A x C/B
A: Output shaft revolution signal from revolution sensor
B: Engine speed signal from ECM
C: Gear ratio determined as gear position which TCM supposes
If the actual gear position is higher than the position (2nd) sup-
posed by TCM, the slip ratio will be more than normal. In case the
ratio exceeds the specified value, TCM judges this diagnosis mal-
function.
This malfunction will be caused when shift solenoid valve B is stuck
open.
Gear position supposed by TCM 1 2 3 4
In case of gear position with no malfunctions 1 2 3 4
In case of gear position with shift solenoid valve B
stuck open43* 3 4
*: P0732 is detected.
Diagnostic trouble code Malfunction is detected when ... Check item (Possible cause)
: A/T 2ND GR FNCTN
A/T cannot be shifted to the 2nd gear
position even if electrical circuit is good.IShift solenoid valve B
IEach clutch
IHydraulic control circuit
: P0732
DTC P0732 IMPROPER SHIFTING TO 2ND GEAR POSITION
Description
AT-126