2001 INFINITI QX4 timing

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

SAT015J
Overrun Clutch Solenoid Valve ControlNBAT0180S0402The overrun clutch solenoid valve is operated by an ON-OFF sig-
nal transmitted by the TCM to provide overrun clutch control
(engine brake control).
When this solenoid valve is ªONº, the pilot pressure drain port
closes. When it is ªOFFº, the drain port opens.
During the solenoid valve ªONº pilot pressure is applied to the end
face of the overrun clutch control valve.
SAT049J
Overrun Clutch Control Valve OperationNBAT0180S0403When the solenoid valve is ªONº, pilot pressure A is applied to the
overrun clutch control valve. This pushes up the overrun clutch
control valve. The line pressure is then shut off so that the clutch
does not engage.
When the solenoid valve is ªOFFº, pilot pressure A is not gener-
ated. At this point, the overrun clutch control valve moves down-
ward by spring force. As a result, overrun clutch operation pressure
is provided by the overrun clutch reducing valve. This causes the
overrun clutch to engage.
In the ª1º position, the overrun clutch control valve remains pushed
down so that the overrun clutch is engaged at all times.
Control ValveNBAT0181FUNCTION OF CONTROL VALVENBAT0181S01
Valve name Function
IPressure regulator valve
IPressure regulator plug
IPressure regulator sleeve plugRegulate oil discharged from the oil pump to provide optimum line pressure for all
driving conditions.
Pressure modifier valve Used as a signal supplementary valve to the pressure regulator valve. Regulates
pressure-modifier pressure (signal pressure) which controls optimum line pressure for
all driving conditions.
Modifier accumulator piston Smooths hydraulic pressure regulated by the pressure modifier valve to prevent pul-
sations.
Pilot valve Regulates line pressure to maintain a constant pilot pressure level which controls
lock-up mechanism, overrun clutch, 3-2 timing required for shifting.
Accumulator control valve
Accumulator control sleeveRegulate accumulator back-pressure to pressure suited to driving conditions.
Manual valve Directs line pressure to oil circuits corresponding to select positions.
Hydraulic pressure drains when the shift lever is in Neutral.
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OVERALL SYSTEM
Control Mechanism (Cont'd)
AT-31

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

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

Items Symptom Condition Diagnostic Item Reference Page
Shift ShockToo sharp a
shock in change
from D
1to D2.ON vehicle1. Throttle position sensor (Adjustment) EC-174
2. Line pressure test AT-62
3. Accumulator servo release AT-273
4. Control valve assembly AT-273
5. A/T fluid temperature sensor AT-105
OFF vehicle 6. Brake band AT-333
Too sharp a
shock in change
from D
2to D3.ON vehicle1. Throttle position sensor (Adjustment) EC-174
2. Line pressure test AT-62
3. Control valve assembly AT-273
OFF vehicle4. High clutch AT-317
5. Brake band AT-333
Too sharp a
shock in change
from D
3to D4.ON vehicle1. Throttle position sensor (Adjustment) EC-174
2. Line pressure test AT-62
3. Control valve assembly AT-273
OFF vehicle4. Brake band AT-333
5. Overrun clutch AT-320
Gear change
shock felt during
deceleration by
releasing accel-
erator pedal.ON vehicle1. Throttle position sensor (Adjustment) EC-174
2. Line pressure test AT-62
3. Overrun clutch solenoid valve AT-185
4. Control valve assembly AT-273
Large shock
changing from 1
2to 11in 1 position.ON vehicle 1. Control valve assembly AT-273
ON vehicle 2. Low & reverse brake AT-324
Improper Shift
TimingToo high a gear
change point from
D
1to D2, from D2to D3, from D3to
D
4.
AT-236, 239, 242ON vehicle1. Throttle position sensor (Adjustment) EC-174
2. Vehicle speed sensor´A/T (Revolution
sensor) and vehicle speed sensor´MTRAT- 111 , 1 9 7
3. Shift solenoid valve A AT-168
4. Shift solenoid valve B AT-172
Gear change
directly from D
1to
D
3occurs.ON vehicle1. Fluid level AT-59
2. Accumulator servo release AT-273
OFF vehicle 3. Brake band AT-333
Too high a
change point from
D
4to D3, from D3to D2, from D2to
D
1.ON vehicle1. Throttle position sensor (Adjustment) EC-174
2. Vehicle speed sensor´A/T (Revolution
sensor) and vehicle speed sensor´MTRAT- 111 , 1 9 7
Kickdown does
not operate when
depressing pedal
in D
4within kick-
down vehicle
speed.ON vehicle1. Throttle position sensor (Adjustment) EC-174
2. Vehicle speed sensor´A/T (Revolution
sensor) and vehicle speed sensor´MTRAT- 111 , 1 9 7
3. Shift solenoid valve A AT-168
4. Shift solenoid valve B AT-172
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Symptom Chart (Cont'd)
AT-82

Items Symptom Condition Diagnostic Item Reference Page
Improper Shift
TimingKickdown oper-
ates or engine
overruns when
depressing pedal
in D
4beyond kick-
down vehicle
speed limit.ON vehicle1. Vehicle speed sensor´A/T (Revolution
sensor) and vehicle speed sensor´MTRAT- 111 , 1 9 7
2. Throttle position sensor (Adjustment) EC-174
3. Shift solenoid valve A AT-168
4. Shift solenoid valve B AT-172
Gear change from
2
2to 23in 2 posi-
tion.ON vehicle1. Park/neutral position (PNP) switch
adjustmentAT-276
Gear change from
1
1to 12in 1 posi-
tion.ON vehicle1. Park/neutral position (PNP) switch
adjustmentAT-276
2. Manual control linkage adjustment AT-276
No Down ShiftFailure to change
gear from D
4to
D
3.ON vehicle1. Fluid level AT-59
2. Throttle position sensor (Adjustment) EC-174
3. Overrun clutch solenoid valve AT-185
4. Shift solenoid valve A AT-168
5. Line pressure solenoid valve AT-162
6. Control valve assembly AT-273
OFF vehicle7. Low & reverse brake AT-324
8. Overrun clutch AT-320
Failure to change
gear from D
3to
D
2or from D4to
D
2.ON vehicle1. Fluid level AT-59
2. Throttle position sensor (Adjustment) EC-174
3. Shift solenoid valve A AT-168
4. Shift solenoid valve B AT-172
5. Control valve assembly AT-273
OFF vehicle6. High clutch AT-317
7. Brake band AT-333
Failure to change
gear from D
2to
D
1or from D3to
D
1.ON vehicle1. Fluid level AT-59
2. Throttle position sensor (Adjustment) EC-174
3. Shift solenoid valve A AT-168
4. Shift solenoid valve B AT-172
5. Control valve assembly AT-273
OFF vehicle6. Low one-way clutch AT-328
7. High clutch AT-317
8. Brake band AT-333
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TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Symptom Chart (Cont'd)
AT-83

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

DescriptionNBAT0228The ECM and TCM provide mutual communication in relation to
engine output control signal (ignition timing retard signal) during
rapid standing starts/acceleration. With this consistent real-time
control, the shifting feel is substantially improved.
TCM TERMINALS AND REFERENCE VALUENBAT0228S01Remarks: Specification data are reference values.
Terminal
No.Wire color Item ConditionJudgement
standard
(Approx.)
33 G/R LAN
ÐÐ
*: This terminal is connected to the ECM.
ON BOARD DIAGNOSIS LOGICNBAT0228S02
Diagnostic trouble code Malfunction is detected when ... Check item (Possible cause)
: A/T COMM LINE
The ECM-A/T communication line is
open or shorted.IHarness or connector
: 12th judgement flicker
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DTC A/T COMMUNICATION LINE
Description
AT-207