Nissan Pathfinder (2012 year). Manual - part 575

A/T CONTROL SYSTEM

TM-27

< SYSTEM DESCRIPTION >

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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

INFOID:0000000007357094

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

PCIA0010E

PCIA0011E

PCIA0012E

August 2012

2012 Pathfinder

TM-28

< SYSTEM DESCRIPTION >

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.

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.

Lock-up Operation Condition Table (Without Manual Mode)

Lock-up Operation Condition Table (With Manual Mode)

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.

PCIA0013E

Select lever

D position

3 position

2 position

Gear position

5

4

3

3

2

Lock-up

×

×

–

–

–

Slip lock-up

–

–

×

–

–

Select lever

D position

M position

Gear  position

5

4

3

5

4

3

2

Lock-up

×

×

–

×

×

–

–

Slip lock-up

–

–

×

–

–

×

–

PCIA0014E

August 2012

2012 Pathfinder

A/T CONTROL SYSTEM

TM-29

< SYSTEM DESCRIPTION >

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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.

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 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.

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 Valve

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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 regulator valve
Pressure regulator plug
Pressure regulator sleeve

Adjusts the oil discharged from the oil pump to the optimum pressure (line pressure) for 
the driving state.

August 2012

2012 Pathfinder

TM-30

< SYSTEM DESCRIPTION >

A/T CONTROL SYSTEM

FUNCTION OF PRESSURE SWITCH 

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.

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.

August 2012

2012 Pathfinder

A/T CONTROL SYSTEM

TM-31

< SYSTEM DESCRIPTION >

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A/T Electrical Parts Location

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1.

O/D OFF indicator lamp (without 
manual mode)

2.

A/T CHECK indicator lamp (with 
manual mode)

3.

Accelerator pedal position sensor

4.

Accelerator pedal

5.

Control valve with TCM*1

6.

A/T assembly harness connector

7.

Overdrive control switch (without 
manual mode)

8.

1st position switch

9.

Manual mode switch (in A/T decline)

AWDIA0958GB

August 2012

2012 Pathfinder

TM-32

< SYSTEM DESCRIPTION >

A/T CONTROL SYSTEM

*1: The following components are included in the control valve with TCM.
• TCM (transmission control module)
• Input speed sensor 1
• Input speed sensor 2
• Output speed sensor
• A/T fluid temperature sensor
• Transmission range switch
• Line pressure solenoid valve
• Torque converter clutch solenoid valve
• Direct clutch solenoid valve
• High and low reverse clutch solenoid valve
• Input clutch solenoid valve
• Front brake solenoid valve
• Low coast brake solenoid valve
• ATF pressure switch 2

August 2012

2012 Pathfinder

A/T SHIFT LOCK SYSTEM

TM-33

< SYSTEM DESCRIPTION >

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A/T SHIFT LOCK SYSTEM

System Description

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• The selector lever cannot be shifted from “P” (Park) unless the brake pedal is depressed and the ignition

switch is in the “ON” position.

• Battery voltage is supplied to the shift lock solenoid by the stop lamp switch.

• Ground is supplied to the shift lock solenoid by the park position switch (shift selector).

• With the ignition switch “ON”, brake pedal depressed and the A/T shift selector in “P” (Park), the shift lock

solenoid is energized, allowing the selector lever to be shifted from Park.

Component Parts Location (With Manual Mode)

INFOID:0000000007357100

1.

A/T shift selector

2.

Shift lock solenoid

3.

Park position switch (shift selector)

4.

Stop lamp switch E38

AWDIA0736GB

August 2012

2012 Pathfinder

TM-34

< SYSTEM DESCRIPTION >

A/T SHIFT LOCK SYSTEM

Component Parts Location (Without Manual Mode)

INFOID:0000000007357101

1.

A/T shift selector

2.

Shift lock solenoid

3.

Park position switch (shift selector)

4.

Stop lamp switch E38

AWDIA0735GB

August 2012

2012 Pathfinder