2009 INFINITI QX56 lock

A/T CONTROL SYSTEMTM-11
< FUNCTION DIAGNOSIS >
CEF
G H
I
J
K L
M A
B
TM
N
O P
 —Operates
 —Operates during “pro gressive” acceleration.
 —Operates and effects power transmission while coasting.
 —Line pressure is applied but does not affect power transmission.
 —Operates under conditions shown in HLR/C Operating Condition
 —Operates under conditions shown in LC/B Operating Condition. Delay control is applied during D (4,3,2,1) ⇒N shift.
POWER TRANSMISSION
“N” Position
N NEUTRAL POSI-
TION
D 1st
Automatic shift
1 ⇔ 2⇔ 3⇔ 4⇔ 5
2nd
3rd
4th
5th1st
4 2nd
Automatic shift
3rd 1
⇔ 2⇔ 3⇔ 4
4th
3 1st
Automatic shift1⇔ 2⇔ 3⇐ 4
2nd
3rd 4th
2 1st
Automatic shift1⇔ 2⇐ 3⇐ 4
2nd
3rd
4th
1 1st
Locks (held sta-tionary in 1st gear)
1 ⇐ 2⇐ 3⇐ 4
2nd
3rd4th
Shift position I/C HLR/C D/C R/B FR/B LC/B Fwd/B
1st
OWC Fwd
OWC 3rd
OWC Remarks
SCIA5642E
Revision: December 20092009 QX56

TM-20
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
TCM Function
INFOID:0000000003771808
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 v ehicle 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 clutch 3. 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 gear 12. Input shaft
13. Mid internal gear 14. Front internal gear 15. Rear carrier
16. Rear sun gear 17. Mid sun gear 18. Front carrier
19. Mid carrier 20. Rear internal gear 21. Output shaft
22. Parking gear 23. Parking pawl
SCIA1519E
Revision: December 20092009 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:0000000003771809
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication li ne 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: December 20092009 QX56

TM-22
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
Input/Output Signal of TCM
INFOID:0000000003771810
*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:0000000003771811
 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 X X X 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 X X X
Input clutch solenoid X X X X
High and low reverse clutch solenoid X X X X
Front brake solenoid X X X 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 X X X
Starter relay XX
Revision: December 20092009 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:0000000003771813
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 c ontrolled by the torque converter clutch solenoid valve,
which is controlled by a signal from TCM, and the to rque 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 position 4 position 3 position 2 position
Gear position 54432
Lock-up ×– ×××
Slip lock-up ××–––
PCIA0014E
Revision: December 20092009 QX56

TM-26
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
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 th is 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 converte r 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 pi ston operating pressure is increased and the coupling 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 tor que fluctuation and lock-up operates from low speed.
This raises the fuel efficiency for 4GR and 5GR at both low speed and when the accelerator has a low
degree of opening.
Engine Brake ControlINFOID:0000000003771814
 The forward one-way clutch transmits the drive force from the engine to the rear wheels. But the reverse
drive from the rear wheels is not transmitted to the engine because the one-way clutch is idling.
Therefore, the low coast brake solenoid is operated to prevent the forward one-way clutch from idling and
the engine brake is operated in the same manner as conventionally.
 The operation of the low coast brake solenoid switches the low coast brake switching valve and controls the
coupling and releasing of the low coast brake.
The low coast brake reducing valve contro ls the low coast brake coupling force.
Control ValveINFOID:0000000003771815
FUNCTION OF CONTROL VALVE
SCIA1520E
Name Function
Torque converter regulator valve In order to prevent the pressure supplied to the torque converter from being excessive,
the line pressure is adjusted to the optimum pressure (torque converter operating pres-
sure).
Pressure regu lator valve
Pressure regulator plug
Pressure regu lator sleeve Adjusts the oil discharged from the oil pump to the optimum pressure (line pressure) for
the driving state.
Front brake control valve When the front brake is coupled, adjusts the line pressure to the optimum pressure (front
brake pressure) and supplies it to the front brake. (In 1GR, 2GR, 3GR, and 5GR, adjusts
the clutch pressure.)
Accumulator control valve Adjusts the pressure (accumulator control pressure) acting on the accumulator piston
and low coast reducing valve to the pressure appropriate to the driving state.
Revision: December 20092009 QX56

A/T CONTROL SYSTEMTM-27
< FUNCTION DIAGNOSIS >
CEF
G H
I
J
K L
M A
B
TM
N
O P
FUNCTION OF PRESSURE SWITCH
Pilot valve A Adjusts the line pressure and produces the constant pressure (pilot pressure) required
for line pressure control, shift change control, and lock-up control.
Pilot valve B Adjusts the line pressure and produces the constant pressure (pilot pressure) required
for shift change control.
Low coast brake switching valve During engine braking, supplies the line pressure to the low coast brake reducing valve.
Low coast brake reducing valve When the low coast brake is coupled, adjusts the line pressure to the optimum pressure
(low coast brake pressure) and supplies it to the low coast brake.
N-R accumulator Produces the stabilizing pressure for when N-R is selected.
Direct clutch piston switching valve Operates in 4GR and switches the direct clutch coupling capacity.
High and low reverse clutch control valve When the high and low reverse clutch is coupled, adjusts the line pressure to the opti-
mum pressure (high and low reverse clutch pressure) and supplies it to the high and low
reverse clutch. (In 1GR, 3GR, 4GR and 5GR, adjusts the clutch pressure.)
Input clutch control valve When the input clutch is coupled, adjusts the line pressure to the optimum pressure (in-
put clutch pressure) and supplies it to the input clutch. (In 4GR and 5GR, adjusts the
clutch pressure.)
Direct clutch control valve When the direct clutch is coupled, adjusts the line pressure to the optimum pressure (di-
rect clutch pressure) and supplies it to the direct clutch. (In 2GR, 3GR, and 4GR, adjusts
the clutch pressure.)
TCC control valve
TCC control plug
TCC control sleeve Switches the lock-up to operating or released. Also, by performing the lock-up operation
transiently, lock-up smoothly.
Torque converter lubrication valve Operates during lock-up to switch the torque converter, cooling, and lubrication system
oil path.
Cool bypass valve Allows excess oil to bypass cooler circuit without being fed into it.
Line pressure relief valve Discharges excess oil from line pressure circuit.
N-D accumulator Produces the stabilizing pressure for when N-D is selected.
Manual valve Sends line pressure to each circuit according to the select position. The circuits to which
the line pressure is not sent drain.
Name Function
Name Function
Pressure switch 2 (LC/B) Detects any malfunction in the low coast brake hydraulic pressure. When it detects any
malfunction, it puts the system into fail-safe mode.
Revision: December 20092009 QX56

A/T SHIFT LOCK SYSTEMTM-29
< FUNCTION DIAGNOSIS >
CEF
G H
I
J
K L
M A
B
TM
N
O P
A/T SHIFT LOCK SYSTEM
System DescriptionINFOID:0000000003771817
 The electrical key interlock mechanism also operates as a shift lock: With the ignition switch turned to ON, the selector lever cannot be shifted from “P” (parking) to any other
position unless the brake pedal is depressed.
With the key removed, the selector lever c annot be shifted from “P” to any other position.
The key cannot be removed unless the selector lever is placed in “P”.
 The shift lock and key interlock mechanisms are controlled by the ON-OFF operation of the shift lock sole-
noid and by the operation of the rotator and slider located inside the key cylinder, respectively.
Component Parts LocationINFOID:0000000003771818
LCIA0326E
Revision: December 20092009 QX56