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
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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
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
–
–
×
–
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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)
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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)
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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
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