2007 INFINITI QX56 Rear brake

AT-30
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A/T CONTROL SYSTEM
“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
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A/T CONTROL SYSTEM
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TCM FunctionINFOID:0000000003532230
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.
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
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A/T CONTROL SYSTEM
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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 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 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.
Engine Brake ControlINFOID:0000000003532236
• 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 controls the low coast brake coupling force.
Control ValveINFOID:0000000003532237
FUNCTION OF CONTROL VALVE
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Name Function
Torque converter regulator valveIn 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 regulator valve
Pressure regulator plug
Pressure regulator sleeveAdjusts the oil discharged from the oil pump to the optimum pressure (line pressure) for
the driving state.
Front brake control valveWhen the front brake is coupled, adjusts the line pressure to the optimum pressure (front
brake pressure) and supplies it to the front brake. (In 1st, 2nd, 3rd, and 5th gears, adjusts
the clutch pressure.)
Accumulator control valveAdjusts the pressure (accumulator control pressure) acting on the accumulator piston
and low coast reducing valve to the pressure appropriate to the driving state.

OVERHAUL
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10. Needle bearing 11. O-ring 12. Front carrier assembly
13. Needle bearing 14. Snap ring 15. Front sun gear
16. 3rd one-way clutch 17. Snap ring 18. Bearing race
19. Needle bearing 20. Seal ring 21. Input clutch assembly
22. Needle bearing 23. Rear internal gear 24. Brake band
25. Mid carrier assembly 26. Needle bearing 27. Bearing race
28. Rear carrier assembly 29. Needle bearing 30. Mid sun gear
31. Seal ring 32. Rear sun gear 33. 1st one-way clutch
34. Snap ring 35. Needle bearing 36. High and low reverse clutch hub
37. Snap ring 38. Bearing race 39. Needle bearing
Apply Genuine Silicone RTV or the equivalent. Refer to GI-45, "
Recommended Chemical Product and Sealant".

OVERHAUL
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2WD models
13. Snap ring 14. Spring retainer 15. Return spring
16. Reverse brake piston 17. D-ring 18. D-ring
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1. Rear oil seal 2. Bracket 3. Bracket
4. Adapter case 5. Parking actuator support 6. Parking pawl
7. Return spring 8. Pawl shaft 9. Self-sealing bolt
10. Bracket 11. Seal ring 12. Needle bearing

DISASSEMBLY
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14. Loosen lock nut and remove band servo anchor end pin from
transmission case.
15. Remove brake band from transmission case.
•To prevent brake linings from cracking or peeling, do not
stretch the flexible band unnecessarily. When removing
the brake band, always secure it with a clip as shown.
Leave the clip in position after removing the brake band.
•Check brake band facing for damage, cracks, wear or
burns.
16. Remove mid carrier assembly and rear carrier assembly as a
unit.
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DISASSEMBLY
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22. Remove mid sun gear assembly, rear sun gear assembly and
high and low reverse clutch hub as a unit.
CAUTION:
Be careful to remove them with bearing races and needle
bearing.
23. Remove high and low reverse clutch assembly from direct clutch
assembly.
CAUTION:
Make sure that needle bearing is installed to the high and
low reverse clutch assembly edge surface.
24. Remove direct clutch assembly from reverse brake.
25. Remove needle bearing from drum support edge surface.
26. Remove snap ring from A/T assembly harness connector.
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AT-286
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ASSEMBLY
36. Install direct clutch assembly in reverse brake.
37. Install high and low reverse clutch assembly in direct clutch
assembly.
38. Align the drive plate using suitable tool.
39. Install high and low reverse clutch hub, mid sun gear assembly
and rear sun gear assembly as a unit.
CAUTION:
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