Nissan Frontier D22. Manual - part 53

 

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Nissan Frontier D22. Manual - part 53

 

 

OVERALL SYSTEM

AT-181

[RE4R01A]

D

E

F

G

H

I

J

K

L

M

A

B

AT

Torque Converter Clutch Solenoid Valve Control

The torque converter clutch solenoid valve is controlled by the TCM.
The plunger closes the drain circuit during the OFF period, and
opens the circuit during the ON period. If the percentage of OFF-time
increases in one cycle, the pilot pressure drain time is reduced and
pilot pressure remains high.

The torque converter clutch piston is designed to slip to adjust the
ratio of ON-OFF, thereby reducing lock-up shock.
OFF-time INCREASING

Amount of drain DECREASING

Pilot pressure HIGH

Lock-up RELEASING

Torque Converter Clutch Control Valve Operation

Lock-up Released
The OFF-duration of the torque converter clutch solenoid valve is long, and pilot pressure is high. The pilot
pressure pushes the end face of the torque converter clutch control valve in combination with spring force to
move the valve to the left. As a result, converter pressure is applied to chamber A (torque converter clutch pis-
ton release side). Accordingly, the torque converter clutch piston remains unlocked.
Lock-up Applied
When the OFF-duration of the torque converter clutch solenoid valve is short, pilot pressure drains and
becomes low. Accordingly, the control valve moves to the right by the pilot pressure of the other circuit and
converter pressure. As a result, converter pressure is applied to chamber B, keeping the torque converter
clutch piston applied.
Also smooth lock-up is provided by transient application and release of the lock-up.

OVERRUN CLUTCH CONTROL (ENGINE BRAKE CONTROL)

Forward one-way clutch is used to reduce shifting shocks in downshifting operations. This clutch transmits
engine torque to the wheels. However, drive force from the wheels is not transmitted to the engine because
the one-way clutch rotates idle. This means the engine brake is not effective.
The overrun clutch operates when the engine brake is needed.

SAT010J

SAT011J

SAT048J

AT-182

[RE4R01A]

OVERALL SYSTEM

Overrun Clutch Operating Conditions

Overrun Clutch Solenoid Valve Control

The overrun clutch solenoid valve is operated by an ON-OFF signal
transmitted by the TCM to provide overrun clutch control (engine
brake control).
When this solenoid valve is ON, the pilot pressure drain port closes.
When it is OFF, the drain port opens.
During the solenoid valve ON pilot pressure is applied to the end
face of the overrun clutch control valve.

Overrun Clutch Control Valve Operation

When the solenoid valve is ON, pilot pressure A is applied to the
overrun clutch control valve. This pushes up the overrun clutch con-
trol valve. The line pressure is then shut off so that the clutch does
not engage.
When the solenoid valve is OFF, pilot pressure A is not generated. At
this point, the overrun clutch control valve moves downward by
spring force. As a result, overrun clutch operation pressure is pro-
vided by the overrun clutch reducing valve. This causes the overrun
clutch to engage.
In the 1 position, the overrun clutch control valve remains pushed
down so that the overrun clutch is engaged at all times.

SAT014J

Gear position

Throttle opening

D position

D

1

 , D

2

 , D

3

  gear position

Less than 3/16

2 position

2

1

 , 2

2

  gear position

1 position

1

1

 , 1

2

  gear position

At any position

SAT015J

SAT049J

OVERALL SYSTEM

AT-183

[RE4R01A]

D

E

F

G

H

I

J

K

L

M

A

B

AT

Control Valve

ECS007LM

FUNCTION OF CONTROL VALVE

Valve name

Function

Pressure regulator valve

Pressure regulator plug

Pressure regulator sleeve plug

Regulate oil discharged from the oil pump to provide optimum line pressure for all driving 
conditions.

Pressure modifier valve

Used as a signal supplementary valve to the pressure regulator valve. Regulates pres-
sure-modifier pressure (signal pressure) which controls optimum line pressure for all 
driving conditions.

Modifier accumulator piston

Smooths hydraulic pressure regulated by the pressure modifier valve to prevent pulsa-
tions.

Pilot valve

Regulates line pressure to maintain a constant pilot pressure level which controls lock-up 
mechanism, overrun clutch, 3-2 timing required for shifting.

Accumulator control valve
Accumulator control sleeve

Regulate accumulator back-pressure to pressure suited to driving conditions.

Manual valve

Directs line pressure to oil circuits corresponding to select positions.
Hydraulic pressure drains when the shift lever is in Neutral.

Shift valve A

Simultaneously switches three oil circuits using output pressure of shift solenoid valve A 
to meet driving conditions (vehicle speed, throttle opening, etc.).
Provides automatic downshifting and up-shifting (1st 

→ 2nd → 3rd → 4th gears/4th → 

3rd 

→ 2nd → 1st gears) in combination with shift valve B.

Shift valve B

Simultaneously switches three oil circuits using output pressure of shift solenoid valve B 
in relation to driving conditions (vehicle speed, throttle opening, etc.).
Provides automatic downshifting and up-shifting (1st 

→ 2nd → 3rd → 4th gears/4th → 

3rd 

→ 2nd → 1st gears) in combination with shift valve A.

Shuttle shift valve S

Switches hydraulic circuits to provide 3-2 timing control and overrun clutch control in 
relation to the throttle opening.
Inactivates the overrun clutch to prevent interlocking in 4th gear when the throttle is wide 
open.

Overrun clutch control valve

Switches hydraulic circuits to prevent engagement of the overrun clutch simultaneously 
with application of the brake band in 4th gear. (Interlocking occurs if the overrun clutch 
engages during D

4

  gear operation.)

4-2 relay valve

Memorizes that the transmission is in 4th gear. Prevents the transmission from down-
shifting from 4th gear to 3rd and then to 2nd in combination with 4-2 sequence valve and 
shift valves A and B when downshifting from 4th to 2nd gear.

4-2 sequence valve

Prevents band servo pressure from draining before high clutch operating pressure and 
band servo releasing pressure drain (from the same circuit) during downshifting from 4th 
to 2nd gear.

Servo charger valve

An accumulator and a one-way orifice are used in the 2nd gear band servo oil circuit to 
dampen shifting shock when shifting from 1st to 2nd gear.
To maintain adequate flow rate when downshifting from 4th or 3rd gear to 2nd gear, the 
servo charger valve directs 2nd gear band servo hydraulic pressure to the circuit without 
going through the one-way orifice when downshifting from 3rd or a higher gear.

3-2 timing valve

Prevents a late operation of the brake band when shifting selector lever from D to 1 or 2 
position while driving in D

3

 .

1 reducing valve

Reduces low & reverse brake pressure to dampen engine-brake shock when downshift-
ing from the 1 position 2nd gear to 1st gear.

Overrun clutch reducing valve

Reduces oil pressure directed to the overrun clutch and prevents engine-brake shock.
In 1 and 2 positions, line pressure acts on the overrun clutch reducing valve to increase 
the pressure-regulating point, with resultant engine brake capability.

Torque converter relief valve

Prevents an excessive rise in torque converter pressure.

AT-184

[RE4R01A]

OVERALL SYSTEM

Torque converter clutch control valve, 
torque converter clutch control plug and 
torque converter clutch control sleeve

Activate or inactivate the lock-up function.
Also provide smooth lock-up through transient application and release of the lock-up 
system.

Shuttle shift valve D

Switches hydraulic circuits so that output pressure of the torque converter clutch sole-
noid valve acts on the lock-up valve in the D position of 2nd, 3rd and 4th gears. (In the D 
position 1st gear, lock-up is inhibited.)

Lock-up control is not affected in D position 2nd, 3rd or 4th gears, unless output pres-
sure of the torque converter clutch solenoid valve is generated by a signal from the 
control unit.

Valve name

Function

 

 

 

 

 

 

 

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