transmission INFINITI QX4 2001 Factory User Guide

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

Pilot pressure generated by the operation of shift solenoid valves
A and B is applied to the end face of shift valves A and B.
The drawing above shows the operation of shift valve B. When the
shift solenoid valve is ªONº, pilot pressure applied to the end face
of the shift valve overcomes spring force, moving the valve upward.
LOCK-UP CONTROLNBAT0180S03The torque converter clutch piston in the torque converter is locked
to eliminate torque converter slip to increase power transmission
efficiency. The solenoid valve is controlled by an ON-OFF duty
signal sent from the TCM. The signal is converted to oil pressure
signal which controls the torque converter clutch piston.
Conditions for Lock-up OperationNBAT0180S0301When vehicle is driven in 4th gear position, vehicle speed and
throttle opening are detected. If the detected values fall within the
lock-up zone memorized in the TCM, lock-up is performed.
Overdrive control switch ON OFF
Selector lever ªDº position
Gear position D
4D3
Vehicle speed sensor More than set value
Throttle position sensor Less than set opening
Closed throttle position switch OFF
A/T fluid temperature sensor More than 40ÉC (104ÉF)
SAT010J
Torque Converter Clutch Solenoid Valve ControlNBAT0180S0302The torque converter clutch solenoid valve is controlled by the
TCM. The plunger closes the drain circuit during the ªOFFº period,
and opens the circuit during the ªONº period. If the percentage of
OFF-time increases in one cycle, the pilot pressure drain time is
reduced and pilot pressure remains high.
The torque converter clutch piston is designed to slip to adjust the
ratio of ON-OFF, thereby reducing lock-up shock.
SAT011J
OFF-time INCREASING
"
Amount of drain DECREASING
"
Pilot pressure HIGH
"
Lock-up RELEASING
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OVERALL SYSTEM
Control Mechanism (Cont'd)
AT-29

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

A/T Fluid CheckNBAT0021FLUID LEAKAGE CHECKNBAT0021S011. Clean area suspected of leaking. Ð for example, mating sur-
face of converter housing and transmission case.
2. Start engine, apply foot brake, place selector lever in ªDº posi-
tion and wait a few minutes.
3. Stop engine.
4. Check for fresh leakage.
SAT638A
FLUID CONDITION CHECKNBAT0021S02
Fluid color Suspected problem
Dark or black with burned odor Wear of frictional material
Milky pinkWater contamination Ð Road water
entering through filler tube or breather
Varnished fluid, light to dark brown
and tackyOxidation Ð Over or under filling, Ð
Overheating
FLUID LEVEL CHECKNBAT0021S03Refer to MA-21, ªChecking A/T Fluidº.
SAT647B
Stall TestNBAT0022STALL TEST PROCEDURENBAT0022S011. Check A/T fluid and engine oil levels. If necessary, add fluid
and oil.
2. Drive vehicle for approx. 10 minutes or until fluid and oil reach
operating temperature.
ATF operating temperature:
50 - 80ÉC (122 - 176ÉF)
SAT513G
3. Set parking brake and block wheels.
4. Install a tachometer where it can be seen by driver during test.
IIt is good practice to put a mark on point of specified
engine rpm on indicator.
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TROUBLE DIAGNOSIS Ð BASIC INSPECTION
A/T Fluid Check
AT-59

Items Symptom Condition Diagnostic Item Reference Page
Slips/Will Not
EngageRaces extremely
fast or slips in
changing from D
4or D3to D1when
depressing pedal.ON vehicle1. Fluid level AT-59
2. Throttle position sensor (Adjustment) EC-174
3. Line pressure test AT-62
4. Line pressure solenoid valve AT-162
5. Control valve assembly AT-273
OFF vehicle6. Forward clutch AT-320
7. Forward one-way clutch AT-330
8. Low one-way clutch AT-328
Vehicle will not
run in any posi-
tion.ON vehicle1. Fluid level AT-59
2. Manual control linkage adjustment AT-276
3. Line pressure test AT-62
4. Line pressure solenoid valve AT-162
OFF vehicle5. Oil pump AT-297
6. High clutch AT-317
7. Brake band AT-333
8. Low & reverse brake AT-324
9. Torque converter AT-286
10. Parking pawl components AT-337
NOT USEDEngine cannot be
started in P and N
positions.
AT-221ON vehicle1. Ignition switch and starter EL-9, and SC-10
2. Manual control linkage adjustment AT-276
3. Park/neutral position (PNP) switch
adjustmentAT-276
Engine starts in
positions other
than P and N.
AT-221ON vehicle1. Manual control linkage adjustment AT-276
2. Park/neutral position (PNP) switch
adjustmentAT-276
Transmission
noise in P and N
positions.ON vehicle1. Fluid level AT-59
2. Line pressure test AT-62
3. Throttle position sensor (Adjustment) EC-174
4. Vehicle speed sensor´A/T (Revolution
sensor) and vehicle speed sensor´MTRAT- 111 , 1 9 7
5. Engine speed signal AT-116
OFF vehicle6. Oil pump AT-297
7. Torque converter AT-286
Vehicle moves
when changing
into P position or
parking gear does
not disengage
when shifted out
of P position.
AT-222ON vehicle 1. Manual control linkage adjustment AT-276
OFF vehicle 2. Parking pawl components AT-337
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Symptom Chart (Cont'd)
AT-88

Items Symptom Condition Diagnostic Item Reference Page
NOT USEDMaximum speed
not attained.
Acceleration poor.ON vehicle1. Fluid level AT-59
2. Park/neutral position (PNP) switch
adjustmentAT-276
3. Shift solenoid valve A AT-168
4. Shift solenoid valve B AT-172
5. Control valve assembly AT-273
OFF vehicle6. Reverse clutch AT-314
7. High clutch AT-317
8. Brake band AT-333
9. Low & reverse brake AT-324
10. Oil pump AT-297
11. Torque converter AT-286
Transmission
noise in D, 2, 1
and R positions.ON vehicle 1. Fluid level AT-59
ON vehicle 2. Torque converter AT-286
Engine brake
does not operate
in ª1º position.
AT-252ON vehicle1. Park/neutral position (PNP) switch
adjustmentAT-276
2. Manual control linkage adjustment AT-276
3. Throttle position sensor (Adjustment) EC-174
4. Vehicle speed sensor´A/T (Revolution
sensor) and vehicle speed sensor´MTRAT- 111 , 1 9 7
5. Shift solenoid valve A AT-168
6. Control valve assembly AT-273
7. Overrun clutch solenoid valve AT-185
OFF vehicle8. Overrun clutch AT-320
9. Low & reverse brake AT-324
Transmission
overheats.ON vehicle1. Fluid level AT-59
2. Engine idling rpm EC-431
3. Throttle position sensor (Adjustment) EC-174
4. Line pressure test AT-62
5. Line pressure solenoid valve AT-162
6. Control valve assembly AT-273
OFF vehicle7. Oil pump AT-297
8. Reverse clutch AT-314
9. High clutch AT-317
10. Brake band AT-333
11. Forward clutch AT-320
12. Overrun clutch AT-320
13. Low & reverse brake AT-324
14. Torque converter AT-286
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Symptom Chart (Cont'd)
AT-90

SAT136K
DescriptionNBAT0028IThe PNP switch assemble includes a transmission range
switch.
IThe transmission range switch detects the selector position
and sends a signal to the TCM.
TCM TERMINALS AND REFERENCE VALUENBAT0028S02Remarks: Specification data are reference values.
Terminal
No.Wire color Item ConditionJudgement
standard
(Approx.)
26 GPNP switch ª1º
position
When setting selector lever to ª1º position.Battery volt-
age
When setting selector lever to other positions. 0V
27 G/WPNP switch ª2º
positionWhen setting selector lever to ª2º position.Battery volt-
age
When setting selector lever to other positions. 0V
34 LPNP switch ªDº
positionWhen setting selector lever to ªDº position.Battery volt-
age
When setting selector lever to other positions. 0V
35 YPNP switch ªRº
positionWhen setting selector lever to ªRº position.Battery volt-
age
When setting selector lever to other positions. 0V
36 PPNP switch ªNº or
ªPº positionWhen setting selector lever to ªNº or ªPº posi-
tion.Battery volt-
age
When setting selector lever to other positions. 0V
ON BOARD DIAGNOSIS LOGICNBAT0028S03
Diagnostic trouble code Malfunction is detected when ... Check item (Possible cause)
: PNP SW/CIRC
TCM does not receive the correct volt-
age signal from the switch based on the
gear position.IHarness or connectors
(The PNP switch circuit is open or
shorted.)
IPNP switch
: P0705
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DTC P0705 PARK/NEUTRAL POSITION SWITCH
Description
AT-99

SAT014K
SAT971J
SAT021J
DIAGNOSTIC TROUBLE CODE (DTC) CONFIRMATION
PROCEDURE
NBAT0039S01CAUTION:
IAlways drive vehicle at a safe speed.
IBe careful not to rev engine into the red zone on the
tachometer.
NOTE:
If ªDIAGNOSTIC TROUBLE CODE CONFIRMATION PROCE-
DUREº has been previously conducted, always turn ignition
switch ªOFFº and wait at least 5 seconds before conducting
the next test.
TESTING CONDITIONS:
Always drive vehicle on a level road to improve the accuracy of
test.
After the repair, perform the following procedure to confirm the
malfunction is eliminated.
With CONSULT-II
1) Start engine and select ªDATA MONITORº mode for ªA/Tº with
CONSULT-II.
2) Make sure that output voltage of A/T fluid temperature sensor
is within the range below.
FLUID TEMP SEN: 0.4 - 1.5V
If out of range, drive the vehicle to decrease the voltage (warm
up the fluid) or stop engine to increase the voltage (cool down
the fluid).
3) Select ª1ST GR FNCTN P0731º of ªDTC WORK SUPPORTº
mode for ªA/Tº with CONSULT-II and touch ªSTARTº.
4) Accelerate vehicle to 10 to 20 km/h (6 to 12 MPH) under the
following condition and release the accelerator pedal com-
pletely.
THROTTLE POSI: Less than 1.0/8 (at all times during step
4)
Selector lever: D position (OD ªONº)
ICheck that ªGEARº shows ª2º after releasing pedal.
5) Depress accelerator pedal to WOT (more than 7.0/8 of
ªTHROTTLE POSIº) quickly from a speed of 10 to 20 km/h (6
to 12 MPH) until ªTESTINGº changes to ªSTOP VEHICLEº or
ªCOMPLETEDº. (It will take approximately 3 seconds.)
If the check result NG appears on CONSULT-II screen, go to
ªDIAGNOSTIC PROCEDUREº, AT-124.
If ªSTOP VEHICLEº appears on CONSULT-II screen, go to the
following step.
ICheck that ªGEARº shows ª1º when depressing accelera-
tor pedal to WOT.
IIf ªTESTINGº does not appear on CONSULT-II for a long
time, select ªSELF-DIAG RESULTSº for ªENGINEº. In case
a 1st trip DTC other than P0731 is shown, refer to appli-
cable ªTROUBLE DIAGNOSIS FOR DTCº.
6) Stop vehicle.
7) Follow the instruction displayed. (Check for normal shifting
referring to the table below.)
Vehicle conditionGear on actual transmission shift pattern when
screen is changed to 1,2,3,4
No malfunction exists 1,2,3,4
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DTC P0731 IMPROPER SHIFTING TO 1ST GEAR POSITION
Description (Cont'd)
AT-121