Infiniti FX35, FX50 (S51). Manual - part 1851

LOCK-UP CONTROL

TM-211

< SYSTEM DESCRIPTION >

[7AT: RE7R01B (VK50VE)]

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LOCK-UP CONTROL

System Diagram

INFOID:0000000005250207

System Description

INFOID:0000000005250208

INPUT/OUTPUT SIGNAL CHART

*: This signal is transmitted via CAN communication line.

SYSTEM DESCRIPTION

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.

Lock-up operation condition table

Torque Converter Clutch Control Valve Control

Lock-up control system diagram

JSDIA1350GB

Sensor

Input signal to TCM

TCM function

Actuator

Input speed sensor 1, 2

Input speed

Lock-up control

Torque converter clutch sole-

noid valve

↓

Torque converter clutch con-

trol valve

Output speed sensor

Vehicle speed

A/T fluid temperature sensor

ATF temperature

ECM

Engine speed signal*

Accelerator pedal position signal*

Closed throttle position signal*

Engine and A/T integrated control signal
(Engine torque)*

Selector lever

“D” position

“M” position

Gear  position

7

6

5

4

3

2

7

6

5

4

3

2

Lock-up

×

–

–

–

–

–

×

×

×

×

×

×

Slip lock-up

×

×

×

×

×

×

×

×

×

×

×

×

TM-212

< SYSTEM DESCRIPTION >

[7AT: RE7R01B (VK50VE)]

LOCK-UP CONTROL

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 steadily 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 states, 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 2GR, 3GR, 4GR, 5GR, 6GR and 7GR.

PCIA0014E

LOCK-UP CONTROL

TM-213

< SYSTEM DESCRIPTION >

[7AT: RE7R01B (VK50VE)]

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Component Parts Location

INFOID:0000000005520217

NOTE:

• The following components are included in A/T shift selector assembly.

- Manual mode select switch

- Manual mode position select switch

- Shift position switch

• The following components are included in control valve with TCM.

- TCM

- Input speed sensor 1, 2

1.

Selector lever position indicator

2.

A/T shift selector assembly

3.

A/T assembly connector

4.

Control valve with TCM

*1

5.

Accelerator pedal position sensor

6.

Manual mode indicator

7.

Shift position indicator

8.

A/T CHECK indicator lamp

9.

Paddle shifter (shift-down)

*2

10. Paddle shifter (shift-up)

*2

A.

Center console

B.

A/T assembly

C.

Accelerator pedal

D.

Combination meter

E.

Steering wheel

JSDIA0787ZZ

TM-214

< SYSTEM DESCRIPTION >

[7AT: RE7R01B (VK50VE)]

LOCK-UP CONTROL

- Output speed sensor

- A/T fluid temperature sensor

- Transmission range switch

- Direct clutch solenoid valve

- High and low reverse clutch solenoid valve

- Input clutch solenoid valve

- Front brake solenoid valve

- Low brake solenoid valve

- Anti-interlock solenoid valve

- 2346 brake solenoid valve

- Line pressure solenoid valve

- Torque converter clutch solenoid valve

*1: Control valve with TCM is included in A/T assembly.

*2: With paddle shifter

Component Description

INFOID:0000000005250210

Name

Function

TCM

The TCM consists of a microcomputer and connectors for signal input and output and 
for power supply. The TCM controls the A/T.

Output speed sensor

TM-257, "Description"

Input speed sensor 1

TM-255, "Description"

Input speed sensor 2

A/T fluid temperature sensor

TM-253, "Description"

Torque converter clutch solenoid valve

TM-274, "Description"

Torque converter clutch control valve

Switches the lock-up to operating or released. Also, by performing the lock-up operation 
transiently, lock-up smoothly.

ECM

EC-588, "System Description"