AT-42
[RE4F04B]
OVERALL SYSTEM
Revision: November 2006
2006 Altima
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 is applied to the over-
run clutch control valve. This pushes up the overrun clutch control
valve. The line pressure is then shut off so that the clutch does not
engage.
When the solenoid valve is OFF, pilot pressure 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.
Control Valve
ECS0095Y
FUNCTION OF CONTROL VALVES
SAT015J
SAT016J
Valve name
Function
Pressure regulator valve, plug and sleeve
plug
Regulates oil discharged from the oil pump to provide optimum line pressure for all driv-
ing conditions.
Pressure modifier valve and sleeve
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.
Pilot valve
Regulates line pressure to maintain a constant pilot pressure level which controls lock-up
mechanism, overrun clutch, shift timing.
Accumulator control valve
Regulates 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.