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Description
General Operation
The Automatic transmission
is
a 3-element torque converter and triple-shaft
electronically controlled
unit which provides 4
speeds forward
and 1
reverse
speed.
The
unit is positioned in line with the engine.
There are
two
types
of automatic transmission
on
CA-V;
the
four-wheel
drive (4WD) model
('97
-
00),
and the
front-wheel
drive (2WD)
model ('98 - 00).
Torque Converter. Gears, and Clutches
The torque converter consists of a pump, turbine. and
stator
assembly in
a single unit.
The
to
rque converter
is connected
to
the
engine
crankshaft.
These
parts
turn together
as
a
unit as
the
engine
turns. Around the outside of the torque
converter
is
a
ring
gear
which meshes
with
the
starter
pinion when the
engine is
started.
The torque
converter assembly serves
as a fly-
wheel
while transmitting
power
to the
transmission
mainshaft.
The transmission has three parallel
shafts:
the mainshaft, the
countershaft,
and the
sub-shaft.
The mainshaft
is in
line with
the engine crankshaft. The mainshaft includes
the
1st,
2nd, and 4th
clutches,
and gears for
3rd, 2nd, 4th,
reverse
and 1st
(3rd
gear
is
integral with the
mainshaft,
while reverse gear is integral with the 4th gear). The
counterShaft
includes the 3rd
clutch
and gears for 3rd, 2nd, 4th, reverse, 1st,
and
park. Reverse and 4th gears can be
locked
to the
countershaft
at its cen
-
ter. providing 4th gear or
reverse,
depending
on
which way
the selector
is
moved.
The
sub-shaft
includes
the
1st-hold
clutch
and gears
for 1st and
4th.
The gears
on
the mainshaft
are
in
constant
mesh with
those
on the
countershaft
and
sub-shaft. When
ce
rtain
combinations
of
gears are engaged by the
clutches,
power is transmitted from the mainshaft to the countershaft to provide
[Q;),
~,~,
W,
and
lID
pOSition
('97
-
98
models),
and
lID,
[II,
ITl,
and
lID
position
('99
- 00
models).
Electronic
Control
The electronic
co
ntrol
system consists
of the Powertrain Control Module
(PCM), sensors. a
linear
solenoid,
and four
solenoid valves. Shifting
and lock-up are electronically
controlled for comfortable driving
under all
conditions.
The PCM is
located below the dashboard, under
the
kick panel on the passenger's
side.
Hydraulic
Control
The valve bodies
include
the main valve body, the secondary
va
lve
body, the regulator
valve
body,
the servo
body,
and
the
lock-up
valve
body. They are bolted to the torque
converter
housing.
The main
valve
body contains the manual valve.
the
1-2
shift valve,
the 2nd
orifice control valve,
the CPS (Clutch Pressure Back-up)
valve, the
modulator
valve,
the
servo
co
ntrol
valve, the
relief valve. and ATF pump
gears.
The secondary valve body
contains
the 2-3
shift
valve
,
the
3-4
shift
va
lve,
the
3-4
orifice
control va
lve,
the 4th exhaust valve and the CPC (Clutch Pressure Control) valve. The regulator valve
body
contains
the pressure regulator
valve, the torque converter check valve,
the
cooler
relief
valve,
and the lock-up
con-
trol valve.
The
servo
body
contains
the servo
valve
which
is
integrated with the reverse shift
fork,
and the
accumulators.
The lock-up valve body contains the lock-up shift valve and the lock-up timing valve. The linear solenoid and the shift
con-
trol
solenoid
valve
AlB
are bolted to the outside of the transmission
housing,
and the lock-up
control solenoid valve
AlB is
bolted to the
outside
of the torque converter
housing.
Fluid from the regulator passes through the manual
valve
to the
various control
valves. The
Clutches
receive fluid from
their
respective feed pipes or internal
hydraulic
circuit.
Shift Control Mechanism
Input
from various sensors located throughout
the
vehic
le
determines which shift
control solenoid valve
the PCM
w ill
acti-
vate.
Activating a
shift
control solenoid valve changes modulator
pressure,
causing
a
shift valve to move. This pressurizes
a line to
one of
the
clutches.
engaging
that
clutch
and
its corresponding
gear.
The
shift control
solenoid valves A and Bare
controlled by
the PCM.
Lock-up Mechanism
In
[Q;]
position ('97
-
98 models)
and
in
lID
position
('99
- 00 models), in 3rd and
4th,
and
in
'Q;]
position in 3rd
('97
- 98
models) and in
lID
position with Over-Drive (O/D) is OFF
(by
pressing the %
switch) in 3rd
('99
- 00
models),
pressurized
fluid is drained from the
back
of the torque
converter
through
a
fluid passage,
causing
the lock-up piston to be held
against the torque
converter cover.
As this takes
place,
the
mainshaft rotates at the
same speed
as the
engine
crankshaft.
Together with hydraulic
contro
l,
the PCM optimizes the timing
of
the
lock-u
p
mechanism.
The
lock-up valves control
the
range of lock-up
according
to
lock-u
p control solenoid valves A and B, and the linear
sOlenoid
.
When lock-up control
solenoid
valves
A and
B
activate,
the
modulator
pressure changes.
The lock-up
control solenoid
valves A and B and
the
linear solenoid are
co
ntrolled by
the
PCM.
(cont'd)
14-3
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