torque INFINITI QX56 2006 Factory Service Manual

AT-2Revision: November 20092006 QX56
CONSULT-II Reference Value .............................
.105
On Board Diagnosis Logic ................................... .105
Possible Cause .................................................... .105
DTC Confirmation Procedure .............................. .105
Wiring Diagram — AT — PNP/SW ...................... .106
Diagnostic Procedure .......................................... .107
DTC P0717 TURBINE REVOLUTION SENSOR ... .109
Description ........................................................... .109
CONSULT-II Reference Value ............................. .109
On Board Diagnosis Logic ................................... .109
Possible Cause .................................................... .109
DTC Confirmation Procedure .............................. .109
Diagnostic Procedure .......................................... .110
DTC P0720 VEHICLE SPEED SENSOR A/T (REV-
OLUTION SENSOR) .............................................. . 111
Description ........................................................... ..111
CONSULT-II Reference Value ...............................111
On Board Diagnosis Logic ................................... ..111
Possible Cause ......................................................111
DTC Confirmation Procedure .............................. ..111
Wiring Diagram — AT — VSSA/T ........................ .113
Diagnostic Procedure .......................................... .114
DTC P0725 ENGINE SPEED SIGNAL .................. .116
Description ........................................................... .116
CONSULT-II Reference Value ............................. .116
On Board Diagnosis Logic ................................... .116
Possible Cause .................................................... .116
DTC Confirmation Procedure .............................. .116
Diagnostic Procedure .......................................... .116
DTC P0740 TORQUE CONVERTER CLUTCH
SOLENOID VALVE ................................................ .118
Description ........................................................... .118
CONSULT-II Reference Value ............................. .118
On Board Diagnosis Logic ................................... .118
Possible Cause .................................................... .118
DTC Confirmation Procedure .............................. .118
Diagnostic Procedure .......................................... .119
DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP) .120
Description ........................................................... .120
CONSULT-II Reference Value ............................. .120
On Board Diagnosis Logic ................................... .120
Possible Cause .................................................... .120
DTC Confirmation Procedure .............................. .120
Diagnostic Procedure .......................................... .121
DTC P0745 LINE PRESSURE SOLENOID VALVE .122
Description ........................................................... .122
CONSULT-II Reference Value ............................. .122
On Board Diagnosis Logic ................................... .122
Possible Cause .................................................... .122
DTC Confirmation Procedure .............................. .122
Diagnostic Procedure .......................................... .123
DTC P1705 THROTTLE POSITION SENSOR ...... .124
Description ........................................................... .124
CONSULT-II Reference Value ............................. .124
On Board Diagnosis Logic ................................... .124
Possible Cause .................................................... .124
DTC Confirmation Procedure .............................. .124
Diagnostic Procedure .......................................... .124
DTC P1710 A/T FLUID TEMPERATURE SENSOR CIRCUIT .................................................................
.127
Description ........................................................... .127
CONSULT-II Reference Value .............................. .127
On Board Diagnosis Logic ................................... .127
Possible Cause .................................................... .127
DTC Confirmation Procedure ............................... .127
Wiring Diagram — AT — FTS .............................. .128
Diagnostic Procedure ........................................... .129
Component Inspection ......................................... .130
DTC P1721 VEHICLE SPEED SENSOR MTR ...... .132
Description ........................................................... .132
CONSULT-II Reference Value .............................. .132
On Board Diagnosis Logic ................................... .132
Possible Cause .................................................... .132
DTC Confirmation Procedure ............................... .132
Diagnostic Procedure ........................................... .133
DTC P1730 A/T INTERLOCK ................................ .134
Description ........................................................... .134
On Board Diagnosis Logic ................................... .134
Possible Cause .................................................... .134
DTC Confirmation Procedure ............................... .134
Judgement of A/T Interlock .................................. .135
Diagnostic Procedure ........................................... .135
DTC P1731 A/T 1ST ENGINE BRAKING .............. .137
Description ........................................................... .137
CONSULT-II Reference Value .............................. .137
On Board Diagnosis Logic ................................... .137
Possible Cause .................................................... .137
DTC Confirmation Procedure ............................... .137
Diagnostic Procedure ........................................... .138
DTC P1752 INPUT CLUTCH SOLENOID VALVE . .139
Description ........................................................... .139
CONSULT-II Reference Value .............................. .139
On Board Diagnosis Logic ................................... .139
Possible Cause .................................................... .139
DTC Confirmation Procedure ............................... .139
Diagnostic Procedure ........................................... .140
DTC P1754 INPUT CLUTCH SOLENOID VALVE
FUNCTION ............................................................. .141
Description ........................................................... .141
CONSULT-II Reference Value .............................. .141
On Board Diagnosis Logic ................................... .141
Possible Cause .................................................... .141
DTC Confirmation Procedure ............................... .141
Diagnostic Procedure ........................................... .142
DTC P1757 FRONT BRAKE SOLENOID VALVE .. .143
Description ........................................................... .143
CONSULT-II Reference Value .............................. .143
On Board Diagnosis Logic ................................... .143
Possible Cause .................................................... .143
DTC Confirmation Procedure ............................... .143
Diagnostic Procedure ........................................... .144
DTC P1759 FRONT BRAKE SOLENOID VALVE
FUNCTION ............................................................. .145
Description ........................................................... .145
CONSULT-II Reference Value .............................. .145
On Board Diagnosis Logic ................................... .145
Possible Cause .................................................... .145

AT-8
PRECAUTIONS
Revision: November 20092006 QX56
Precautions ECS00CDL

Before connecting or disconnecting the A/T assembly har-
ness connector, turn ignition switch “OFF” and disconnect
negative battery cable. Because battery voltage is applied
to TCM even if ignition switch is turned “OFF”.

After performing each TROUBLE DIAGNOSIS, perform
“DTC (Diagnostic Trouble Code) CONFIRMATION PROCE-
DURE”.
If the repair is completed the DTC should not be displayed
in the “DTC CONFIRMATION PROCEDURE”.

Always use the specified brand of ATF. Refer to MA-11, "RECOMMENDED FLUIDS AND LUBRICANTS" .

Use paper rags not cloth rags during work.

After replacing the ATF, dispose of the waste oil using the methods prescribed by law, ordinance, etc.

Before proceeding with disassembly, thoroughly clean the outside of the transmission. It is important to
prevent the internal parts from becoming contaminated by dirt or other foreign matter.

Disassembly should be done in a clean work area.

Use lint-free cloth or towels for wiping parts clean. Common shop rags can leave fibers that could interfere
with the operation of the transmission.

Place disassembled parts in order for easier and proper assembly.

All parts should be carefully cleaned with a general purpose, non-flammable solvent before inspection or
reassembly.

Gaskets, seals and O-rings should be replaced any time the transmission is disassembled.

It is very important to perform functional tests whenever they are indicated.

The valve body contains precision parts and requires extreme care when parts are removed and serviced.
Place disassembled valve body parts in order for easier and proper assembly. Care will also prevent
springs and small parts from becoming scattered or lost.

Properly installed valves, sleeves, plugs, etc. will slide along bores in valve body under their own weight.

Before 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.

Extreme care should be taken to avoid damage to O-rings, seals and gaskets when assembling.

Clean or replace ATF cooler if excessive foreign material is found in oil pan or clogging strainer. Refer to
AT- 1 4 , "
A/T Fluid Cooler Cleaning" .

After overhaul, refill the transmission with new ATF.

When 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 under “Changing A/T Fluid” in the AT section when changing A/T fluid. Refer
to AT- 1 2 , "
Changing Automatic Transmission Fluid (ATF)" , AT- 1 2 , "Checking Automatic Transmission
Fluid (ATF)" .
SEF289H
SEF217U

A/T CONTROL SYSTEMAT-17
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A/T CONTROL SYSTEMPFP:31036
Cross-Sectional View (2WD models)ECS00CDT
1. Front planetary gear2. Mid planetary gear 3. Rear planetary gear
4. Direct clutch 5. High and low reverse clutch 6. Reverse brake
7. Drum support 8. Forward brake 9. Low coast brake
10. Input shaft 11. Torque converter 12. Oil pump
13. Front brake 14. 3rd one-way clutch 15. Input clutch
16. 1st one-way clutch 17. Control valve with TCM 18. Forward one-way clutch
19. Rear extension 20. Output shaft
SCIA5267E

AT-18
A/T CONTROL SYSTEM
Revision: November 20092006 QX56
Cross-Sectional View (4WD models)ECS00CDU
1. Front planetary gear2. Mid planetary gear 3. Rear planetary gear
4. Direct clutch 5. High and low reverse clutch 6. Reverse brake
7. Drum support 8. Forward brake 9. Low coast brake
10. Input shaft 11. Torque converter 12. Oil pump
13. Front brake 14. 3rd one-way clutch 15. Input clutch
16. 1st one-way clutch 17. Control valve with TCM 18. Forward one-way clutch
19. Adapter case 20. Output shaft
SCIA5268E

A/T CONTROL SYSTEMAT-21
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POWER TRANSMISSION
“N” Position
Since both the forward brake and the reverse brake are released, torque from the input shaft drive is not trans-
mitted to the output shaft.
“P” Position

The same as for the “N” position, both the forward brake and the reverse brake are released, so torque
from the input shaft drive is not transmitted to the output shaft.

The parking pawl linked with the select lever meshes with the parking gear and fastens the output shaft
mechanically.
SCIA5642E
1. Front brake 2. Input clutch3. Direct clutch
4. High and low reverse clutch 5. Reverse brake 6. Forward brake
7. Low coast brake 8. 1st one-way clutch9. Forward one-way clutch
10. 3rd one-way clutch 11. Front sun gear12. Input shaft
13. Mid internal gear 14. Front internal gear15. Rear carrier
16. Rear sun gear 17. Mid sun gear18. Front carrier
19. Mid carrier 20. Rear internal gear21. Output shaft
22. Parking gear 23. Parking pawl
PCIA0003J

AT-30
A/T CONTROL SYSTEM
Revision: November 20092006 QX56
TCM FunctionECS00CDW
The function of the TCM is to:

Receive input signals sent from various switches and sensors.

Determine required line pressure, shifting point, lock-up operation, and engine brake operation.

Send required output signals to the respective solenoids.
CONTROL SYSTEM OUTLINE
The automatic transmission senses vehicle operating conditions through various sensors or signals. It always
controls the optimum shift position and reduces shifting and lock-up shocks.
CONTROL SYSTEM DIAGRAM
SENSORS (or SIGNALS)

TCM

ACTUATORS
PNP switch
Accelerator pedal position sensor
Closed throttle position signal
Wide open throttle position signal
Engine speed signal
A/T fluid temperature sensor
Revolution sensor
Vehicle speed signal
Stop lamp switch signal
Turbine revolution sensor
1st position switch signal
4th position switch signal
ATF pressure switch signal
Tow mode switch signal Shift control
Line pressure control
Lock-up control
Engine brake control
Timing control
Fail-safe control
Self-diagnosis
CONSULT-II communication line
Duet-EA control
CAN system
Input clutch solenoid valve
Direct clutch solenoid valve
Front brake solenoid valve
High and low reverse clutch
solenoid valve
Low coast brake solenoid valve
Torque converter clutch solenoid
valve
Line pressure solenoid valve
A/T CHECK indicator lamp
Starter relay
Back-up lamp relay
SCIA5624E

AT-32
A/T CONTROL SYSTEM
Revision: November 20092006 QX56
Line Pressure ControlECS00CDZ

When an input torque signal equivalent to the engine drive force is sent from the ECM to the TCM, the
TCM controls the line pressure solenoid.

This line pressure solenoid controls the pressure regulator valve as the signal pressure and adjusts the
pressure of the operating oil discharged from the oil pump to the line pressure most appropriate to the
driving state.
LINE PRESSURE CONTROL IS BASED ON THE TCM LINE PRESSURE CHARACTERISTIC
PATTERN

The TCM has stored in memory a number of patterns for the optimum line pressure characteristic for the
driving state.

In order to obtain the most appropriate line pressure characteristic to meet the current driving state, the
TCM controls the line pressure solenoid current value and thus controls the line pressure.
Normal Control
Each clutch is adjusted to the necessary pressure to match the
engine drive force.
Back-up Control (Engine Brake)
When the select operation is performed during driving and the trans-
mission is shifted down, the line pressure is set according to the
vehicle speed.
PCIA0007E
PCIA0008E
PCIA0009E

A/T CONTROL SYSTEMAT-33
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During Shift Change
The necessary and adequate line pressure for shift change is set.
For this reason, line pressure pattern setting corresponds to input
torque and gearshift selection. Also, line pressure characteristic is
set according to engine speed, during engine brake operation.
At Low Fluid Temperature
When the A/T fluid temperature drops below the prescribed tempera-
ture, in order to speed up the action of each friction element, the line
pressure is set higher than the normal line pressure characteristic.
Shift ControlECS00CE0
The clutch pressure control solenoid is controlled by the signals from the switches and sensors. Thus, the
clutch pressure is adjusted to be appropriate to the engine load state and vehicle driving state. It becomes
possible to finely control the clutch hydraulic pressure with high precision and a smoother shift change charac-
teristic is attained.
SHIFT CHANGE
The clutch is controlled with the optimum timing and oil pressure by the engine speed, engine torque informa-
tion, etc.
PCIA0010E
PCIA0011E
PCIA0012E

AT-34
A/T CONTROL SYSTEM
Revision: November 20092006 QX56
Shift Change System Diagram
*1: Full phase real-time feedback control monitors movement of gear ratio at gear change, and controls oil
pressure at real-time to achieve the best gear ratio.
Lock-up ControlECS00CE1
The torque converter clutch piston in the torque converter is engaged to eliminate torque converter slip to
increase power transmission efficiency.
The torque converter clutch control valve operation is controlled by the torque converter clutch solenoid valve,
which is controlled by a signal from TCM, and the torque converter clutch control valve engages or releases
the torque converter clutch piston.
Lock-up Operation Condition Table
TORQUE CONVERTER CLUTCH CONTROL VALVE CONTROL
Lock-up Control System Diagram
Lock-up Released

In the lock-up released state, the torque converter clutch control valve is set into the unlocked state by the
torque converter clutch solenoid and the lock-up apply pressure is drained.
In this way, the torque converter clutch piston is not coupled.
PCIA0013E
Select leverD position4 position 3 position 2 position
G ea r p osit io n 54432
Lock-up ×–×××
Slip lock-up ××–––
PCIA0014E

A/T CONTROL SYSTEMAT-35
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Lock-up Applied

In the lock-up applied state, the torque converter clutch control valve is set into the locked state by the
torque converter clutch solenoid and lock-up apply pressure is generated.
In this way, the torque converter clutch piston is pressed and coupled.
SMOOTH LOCK-UP CONTROL
When shifting from the lock-up released state to the lock-up applied state, the current output to the torque con-
verter clutch solenoid is controlled with the TCM. In this way, when shifting to the lock-up applied state, the
torque converter clutch is temporarily set to the half-clutched state to reduce the shock.
Half-clutched State

The current output from the TCM to the torque converter clutch solenoid is varied to gradually increase
the torque converter clutch solenoid pressure.
In this way, the lock-up apply pressure gradually rises and while the torque converter clutch piston is put
into half-clutched status, the torque converter clutch piston operating pressure is increased and the cou-
pling is completed smoothly.
Slip Lock-up Control

In the slip region, the torque converter clutch solenoid current is controlled with the TCM to put it into the
half-clutched state. This absorbs the engine torque fluctuation and lock-up operates from low speed.
This raises the fuel efficiency for 4th and 5th gears at both low speed and when the accelerator has a low
degree of opening.