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A/T CONTROL SYSTEM
AT-27
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“D”, “4”, “3” Positions 3rd Gear
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 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
SCIA1516E
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AT-28
A/T CONTROL SYSTEM
Revision: August 20072004 QX56
“D”, “4” Positions 4th 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.
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
planetary gears rotate forward as one unit.
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
SCIA1517E
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A/T CONTROL SYSTEM
AT-29
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“D” Position 5th Gear
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 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
SCIA1518E
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AT-30
A/T CONTROL SYSTEM
Revision: August 20072004 QX56
“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 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
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A/T CONTROL SYSTEM
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TCM FunctionUCS002CE
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 signalShift 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 systemInput 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
Sta rte r re lay
Back-up lamp relay
LCIA0317E
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AT-32
A/T CONTROL SYSTEM
Revision: August 20072004 QX56
CAN CommunicationUCS002CF
SYSTEM DESCRIPTION
Refer to LAN-5, "CAN Communication Unit" .
Input/Output Signal of TCMUCS002CG
*1: Spare for vehicle speed sensor·A/T (revolution 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 communicationsControl itemLine
pressure
controlVehicle
speed
controlShift
controlLock-up
controlEngine
brake
controlFail-safe
function
(*3)Self-diag-
nostics
function
InputAccelerator pedal position signal
(*4)XXXXXXX
Vehicle speed sensor A/T
(revolution sensor)XXXX XX
Vehicle speed sensor MTR
(*1) (*4)XXXX X
Closed throttle position signal
(*4)(*2) X (*2) X X (*2) X X
Wide open throttle position signal
(*4)(*2) X (*2) X (*2) X X
Turbine revolution sensor 1 X X X X X
Turbine revolution sensor 2
(for 4th speed only)XX X XX
Engine speed signals
(*4)XX
PNP switch XXXXXXX
A/T fluid temperature sensors 1, 2 X X X X X X X
ICC or
ASCDOperation signal
(*4)XXXX
Overdrive cancel
signal
(*4)XXX
TCM power supply voltage signal X X X X X X
Out-
putDirect clutch solenoid (ATF pres-
sure switch 5)XX XX
Input clutch solenoid (ATF pressure
switch 3)XX XX
High and low reverse clutch sole-
noid (ATF pressure switch 6)XX XX
Front brake solenoid (ATF pressure
switch 1)XX XX
Low coast brake solenoid (ATF
pressure switch 2)XX XXX
Line pressure solenoid X X X X X X X
TCC solenoid X X X
Starte r re la yXX
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A/T CONTROL SYSTEM
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Line Pressure ControlUCS002C H
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 valve 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
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AT-34
A/T CONTROL SYSTEM
Revision: August 20072004 QX56
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 ControlUCS002CI
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
PCIA0 011 E
PCIA0012E
