OVERALL SYSTEM
AT-43
[RE4F04B]
D
E
F
G
H
I
J
K
L
M
A
B
AT
Revision: November 2006
2006 Altima
Shift valve B
Simultaneously switches two 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.
Overrun clutch control valve
Switches hydraulic circuits to prevent engagement of the overrun clutch simultaneously
with application of the brake band in D
4
. (Interlocking occurs if the overrun clutch
engages during D
4
.)
“1” reducing valve
Reduces low & reverse brake pressure to dampen engine-brake shock when down-shift-
ing from the 1 position 1
2
to 1
1
.
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.
Torque converter clutch control valve, plug
and sleeve
Activates or inactivates the lock-up function.
Also provides smooth lock-up through transient application and release of the lock-up
system.
1-2 accumulator valve and piston
Dampens the shock encountered when 2nd gear band servo contracts, and provides
smooth shifting.
3-2 timing valve
Switches the pace that oil pressure is released depending on vehicle speed; maximizes
the high clutch release timing, and allows for soft down shifting.
Shuttle valve
Determines if the overrun clutch solenoid valve should control the 3-2 timing valve or the
overrun clutch control valve and switches between the two.
Cooler check valve
At low speeds and with a small load when little heat is generated, saves the volume of
cooler flow, and stores the oil pressure for lock up.
Valve name
Function