Nissan Pathfinder (2005 year). Instruction — part 7
A/T CONTROL SYSTEM
AT-27
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AT
2005 Pathfinder
“D” Position 5th Gear
●
The front brake fastens the front sun gear.
●
The input clutch is coupled and the front internal gear and mid internal gear are connected.
●
The high and low reverse clutch is coupled and the mid sun gear and rear sun gear are connected.
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
SCIA4984E
AT-28
A/T CONTROL SYSTEM
2005 Pathfinder
“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
SCIA1519E
A/T CONTROL SYSTEM
AT-29
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2005 Pathfinder
TCM Function
UCS0031E
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.
CONTROL SYSTEM DIAGRAM
SENSORS (or SIGNALS)
Þ
TCM
Þ
ACTUATORS
PNP switch
Accelerator pedal position sensor
Closed throttle position signal
Wide open throttle position signal
Engine speed signal
A/T fluid temperature sensor
Revolution sensor
Vehicle speed signal
Stop lamp switch signal
Turbine revolution sensor
1st position switch signal
Overdrive control switch signal
ATF pressure switch signal
Shift control
Line pressure control
Lock-up control
Engine brake control
Timing control
Fail-safe control
Self-diagnosis
CONSULT-II communication line
Duet-EA control
CAN system
Input clutch solenoid valve
Direct clutch solenoid valve
Front brake solenoid valve
High and low reverse clutch
solenoid valve
Low coast brake solenoid valve
Torque converter clutch solenoid
valve
Line pressure solenoid valve
O/D OFF indicator lamp
Starter relay
Back-up lamp relay
SCIA6495E
AT-30
A/T CONTROL SYSTEM
2005 Pathfinder
CAN Communication
UCS0031F
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only. For details, refer to
.
Input/Output Signal of TCM
UCS0031G
*1: Spare for vehicle speed sensor·A/T (revolution sensor)
*2: Spare for accelerator pedal position signal
*3: If these input and output signals are different, the TCM triggers the fail-safe function.
*4: CAN communications
Control item
Line
pressure
control
Vehicle
speed
control
Shift
control
Lock-up
control
Engine
brake
control
Fail-safe
function
(*3)
Self-diag-
nostics
function
Input
Accelerator pedal position signal
(*4)
X
X
X
X
X
X
X
Vehicle speed sensor A/T
(revolution sensor)
X
X
X
X
X
X
Vehicle speed sensor MTR
(*1) (*4)
X
X
X
X
X
Closed throttle position signal
(*4)
X(*2)
X(*2)
X
X(*2)
X
Wide open throttle position signal
(*4)
X(*2)
X(*2)
X(*2)
X
Turbine revolution sensor 1
X
X
X
X
X
Turbine revolution sensor 2
(for 4th speed only)
X
X
X
X
X
Engine speed signals
(*4)
X
X
PNP switch
X
X
X
X
X
X
X
Stop lamp switch signal
(*4)
X
X
X
A/T fluid temperature sensors 1, 2
X
X
X
X
X
X
X
ASCD
Operation signal
(*4)
X
X
X
X
Overdrive cancel
signal
(*4)
X
X
X
TCM power supply voltage signal
X
X
X
X
X
X
Out-
put
Direct clutch solenoid (ATF pres-
sure switch 5)
X
X
X
X
Input clutch solenoid (ATF pressure
switch 3)
X
X
X
X
High and low reverse clutch sole-
noid (ATF pressure switch 6)
X
X
X
X
Front brake solenoid (ATF pressure
switch 1)
X
X
X
X
Low coast brake solenoid (ATF
pressure switch 2)
X
X
X
X
X
Line pressure solenoid
X
X
X
X
X
X
X
TCC solenoid
X
X
X
Starter relay
X
X
A/T CONTROL SYSTEM
AT-31
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2005 Pathfinder
Line Pressure Control
UCS0031H
●
When an input torque signal equivalent to the engine drive force is sent from the ECM to the TCM, the
TCM controls the line pressure solenoid.
●
This line pressure solenoid controls the pressure regulator valve as the signal pressure and adjusts the
pressure 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
PATTERN
●
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 value 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.
PCIA0007E
PCIA0008E
PCIA0009E
AT-32
A/T CONTROL SYSTEM
2005 Pathfinder
During Shift Change
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
UCS0031I
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.
PCIA0010E
PCIA0011E
PCIA0012E
A/T CONTROL SYSTEM
AT-33
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2005 Pathfinder
Shift Change System Diagram
*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
UCS0031J
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
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
2
Lock-up
×
–
×
×
Slip lock-up
×
×
–
–
PCIA0014E
AT-34
A/T CONTROL SYSTEM
2005 Pathfinder
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 cou-
pling 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 Control
UCS0031K
●
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.
SCIA1520E
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