Infiniti FX35 / FX45. Instruction - page 26

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< SERVICE INFORMATION >

A/T CONTROL SYSTEM

• This line pressure solenoid controls the pressure regulator 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 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.

During Shift Change

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A/T CONTROL SYSTEM

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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 Control

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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

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< SERVICE INFORMATION >

A/T CONTROL SYSTEM

*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.

BLIPPING CONTROL

This system makes transmission clutch engage readily by controlling (synchronizing) engine revolution
according to the (calculation of) engine revolution after shifting down.
• “BLIPPING CONTROL” functions.
- When downshifting by accelerator pedal depression at “D” position.
- When downshifting under the manual mode.
• TCM selects “BLIPPING CONTROL” or “NORMAL SHIFT CONTROL” according to the gear position, the

select lever position, the engine torque and the speed when accelerating by accelerator pedal depression.

• Revolution control demand signal is transmitted from TCM to ECM under “BLIPPING CONTROL”.
• TCM synchronizes engine revolution according to the revolution control demand signal.

Shift Change System Diagram

Lock-up Control

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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.

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A/T CONTROL SYSTEM

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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

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.

Engine Brake Control

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• 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.

selector lever

D position

M5 position

M4 position

M3 position

Gear position

5

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Lock-up

×

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Slip lock-up

×

×

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