INFINITI QX56 2010 Factory Service Manual

TM-16
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
“D”, “4”, “3” Positions 3GR
• The front brake fastens the front sun gear.
• The direct clutch is coupled, and the rear carrier and rear sun gear are connected.
• The high and low reverse clutch is coupled and the mid sun gear and rear sun gear are connected.
1. Front brake2. Input clutch3. Direct clutch
4. High and low reverse clutch 5. Reverse brake 6. Forward brake
7. Low coast brake 8. 1st one-way clutch 9. 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
SCIA1515E
Revision: April 20092010 QX56

A/T CONTROL SYSTEMTM-17
< FUNCTION DIAGNOSIS >
CEF
G H
I
J
K L
M A
B
TM
N
O P
“D”, “4” Positions 4GR
• The direct clutch is coupled, and the rear carrier and rear sun gear are connected.
• The high and low reverse clutch is coupled and the mid sun gear and rear sun gear are connected.
• The input clutch is coupled and the front internal gear and mid internal gear are connected.
• The drive power is conveyed to the front internal gear
, mid internal gear, and rear carrier and the three plan-
etary gears rotate forward as one unit.
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
SCIA1516E
Revision: April 20092010 QX56

TM-18
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
“D” Position 5GR
• The front brake fastens the front sun gear.
• The input clutch is coupled and the front internal gear and mid internal gear are connected.
• The high and low reverse clutch is coupled and the mid sun gear and rear sun gear are connected.
1. Front brake2. Input clutch3. Direct clutch
4. High and low reverse clutch 5. Reverse brake 6. Forward brake
7. Low coast brake 8. 1st one-way clutch 9. 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
SCIA1517E
Revision: April 20092010 QX56

A/T CONTROL SYSTEMTM-19
< FUNCTION DIAGNOSIS >
CEF
G H
I
J
K L
M A
B
TM
N
O P
“R” Position
• The front brake fastens the front sun gear.
• The high and low reverse clutch is coupled, and the mid sun gear and rear sun gear are connected.
• The reverse brake fastens the rear carrier.
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
SCIA4984E
Revision: April 20092010 QX56

TM-20
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
TCM Function
INFOID:0000000005148510
The function of the TCM is to:
• Receive input signals sent from various switches and sensors.
• Determine required line pressure, shifting poi nt, 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 vari ous sensors or signals. It always
controls the optimum shift position and reduces shifting and lock-up shocks.
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 clutch 9. 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
SCIA1519E
Revision: April 20092010 QX56

A/T CONTROL SYSTEMTM-21
< FUNCTION DIAGNOSIS >
CEF
G H
I
J
K L
M A
B
TM
N
O P
CONTROL SYSTEM DIAGRAM
CAN CommunicationINFOID:0000000005148511
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only. For details, refer to LAN-4,
"System Description".
SENSORS (or SIGNALS)
⇒TCM
⇒ACTUATORS
Transmission range switch
Accelerator pedal position sensor
Closed throttle position signal
Wide open throttle position signal
Engine speed signal
A/T fluid temperature sensor
Output speed sensor
Vehicle speed signal
Stop lamp switch signal
Input speed sensor
1st position switch signal
4th position switch signal
ATF pressure switch 2 signal
Tow mode switch signal Shift control
Line pressure control
Lock-up control
Engine brake control
Timing control
Fail-safe control
Self-diagnosis
CONSULT-III co
mmunication
line
Duet-EA control
CAN system Input clutch solenoid valve
Direct clutch solenoid valve
Front brake solenoid valve
High and low reverse clutch sole-
noid 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
JSDIA1315GB
Revision: April 20092010 QX56

TM-22
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
Input/Output Signal of TCM
INFOID:0000000005148512
*1: Spare for output speed sensor
*2: Spare for accelerator pedal position signal
*3: If these input and output signals are different, the TCM triggers the fail-safe function.
*4: CAN comm unications
*5: Used as a condition for starting self-diagnostics; if self-diagnostics are not started, it is judged that there is some kin d of error.
*6: A/T fluid temperature sensor 2 does not have any function.
Line Pressure ControlINFOID:0000000005148513
• 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.
Control item Line
pres- sure
control Vehicle
speed
control S h i f t
control Lock-up
control Engine
brake
control Fail-safe
function (*3) Self-diag-
nostics
function
Input Accelerator pedal position signal
(*4)XXXXX X X
Output speed sensor X X X X X X
Vehicle speed signal
(*1) (*4)XXXX X
Closed throttle position signal
(*4)(*2) X (*2) X X (*2) X(*5) X
Wide open throttle position signal
(*4)(*2) X (*2) X (*2) X(*5) X
Input speed sensor 1 X XXX X
Input speed sensor 2
(for 4th speed only) XX X
X X
Engine speed signals
(*4)XX
Transmission range switch X X X X X X X
Stop lamp switch signal
(*4)XXX (*5) X
A/T fluid temperature sensors 1, 2 (*6) X X X X X X X
ASCD Operation signal
(*4)XXXX
Overdrive cancel sig-
nal
(*4)XXX
TCM power supply voltage signal X X X X X X
Output Direct clutch solenoid
X XX X
Input clutch solenoid X XX X
High and low reverse clutch solenoid X XX X
Front brake solenoid X XX X
Low coast brake solenoid (ATF pressure
switch 2) XX X X X
Line pressure solenoid X X X X X X X
TCC solenoid XX X
Starter relay XX
Revision: April 20092010 QX56

A/T CONTROL SYSTEMTM-23
< FUNCTION DIAGNOSIS >
CEF
G H
I
J
K L
M A
B
TM
N
O P
• This line pressure solenoid controls the pressure regulat or valve as the signal pressure and adjusts the pres-
sure 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 PAT-
TERN
• The TCM has stored in memory a number of patterns fo r the optimum line pressure characteristic for the
driving state.
• In order to obtain the most appropriate line pressure char acteristic 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.
During Shift Change
PCIA0007E
PCIA0008E
PCIA0009E
Revision: April 20092010 QX56

TM-24
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
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 ControlINFOID:0000000005148514
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.
Shift Change System Diagram
PCIA0010E
PCIA0011E
PCIA0012E
Revision: April 20092010 QX56

A/T CONTROL SYSTEMTM-25
< FUNCTION DIAGNOSIS >
CEF
G H
I
J
K L
M A
B
TM
N
O P
*1: Full phase real-time feedback control monitors move ment of gear ratio at gear change, and controls oil
pressure at real-time to achieve the best gear ratio.
Lock-up ControlINFOID:0000000005148515
The torque converter clutch piston in the torque conv erter is engaged to eliminate torque converter slip to
increase power transmission efficiency.
The torque converter clutch control valve operation is controlled by the torque conver ter 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.
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
PCIA0013E
Select lever D position4 position 3 position 2 position
G ear p osit io n 54432
Lock-up ×– ×××
Slip lock-up ××–––
PCIA0014E
Revision: April 20092010 QX56