Chrysler 1998 Voyager Service Manual page 1477

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GENERAL INFORMATION (Continued)
If there is any doubt about its condition, drain out a
sample for a double check.
SELECTION OF LUBRICANT
It is important that the proper lubricant be used in
these transmissions. Mopar ATF PLUS 3 (Automatic
Transmission Fluid- type 7176) should be used to aid
in ensuring optimum transmission performance. It is
important that the transmission fluid be maintained
at the prescribed level using the recommended fluids.
SPECIAL ADDITIVES
Chrysler Corporation does not recommend the
addition of any fluids to the transmission, other than
fluid listed above. An exception to this policy is the
use of special dyes to aid in detecting fluid leaks. The
use of transmission sealers should be avoided, since
they may adversely affect seals.
DESCRIPTION AND OPERATION
TORQUE CONVERTER CLUTCH
A torque converter clutch is standard on all vehi-
cles. The torque converter clutch is activated only in
direct drive and is controlled by the engine electron-
ics. A solenoid on the valve body, is powered by the
powertrain control module to activate torque con-
verter clutch.
HYDRAULIC CONTROL SYSTEM
The hydraulic control system makes the transaxle
fully automatic, and has four important functions to
perform. The components of any automatic control
system may be grouped into the following basic
groups:
The pressure supply system, the pressure regulat-
ing valves, the flow control valves, the clutches, and
band servos.
Taking each of these basic groups or systems in
turn, the control system may be described as follows:
PRESSURE SUPPLY SYSTEM
The pressure supply system consists of an oil pump
driven by the engine through the torque converter.
The single pump furnishes pressure for all the
hydraulic and lubrication requirements. Oil pump
housing assemblies are available with prese-
lected pump gears.
PRESSURE REGULATING VALVES
The pressure regulating valve controls line pres-
sure dependent on throttle opening. The governor
valve transmits regulated pressure to the valve body
(in conjunction with vehicle speed) to control upshift
and downshift.
TRANSAXLE AND POWER TRANSFER UNIT
The throttle valve transmits regulated pressure to
the transaxle (dependent on throttle position) to con-
trol upshift and downshift.
FLOW CONTROL VALVES
The manual valve provides the different transaxle
drive ranges as selected by the vehicle operator.
The 1-2 shift valve automatically shifts the tran-
saxle from first to second or from second to first,
depending on the vehicle operation.
The 2-3 shift valve automatically shifts the tran-
saxle from second to third or from third to second
depending on the vehicle operation.
The kickdown valve makes possible a forced down-
shift from third to second, second to first, or third to
first (depending on vehicle speed). This can be done
by depressing the accelerator pedal past the detent
feel near wide open throttle.
The shuttle valve has two separate functions and
performs each independently of the other. The first is
providing fast release of the kickdown band, and
smooth front clutch engagement when a lift-foot
upshift from second to third is made. The second
function is to regulate the application of the kick-
down servo and band when making third to second
kickdown.
The by-pass valve provides for smooth application
of the kickdown band on 1-2 upshifts.
The torque converter clutch solenoid allows for the
electronic control of the torque converter clutch. It
also disengages the torque converter at closed throt-
tle. This is done during engine warm-up, and part-
throttle acceleration.
The switch valve directs oil to apply the torque
converter clutch in one position. The switch valve
releases the torque converter clutch in the other posi-
tion.
CLUTCHES, BAND SERVOS, AND ACCUMULATOR
The front and rear clutch pistons, and both servo
pistons are moved hydraulically to engage the
clutches and apply the bands. The pistons are
released by spring tension when hydraulic pressure
is released. On the 2-3 upshift, the kickdown servo
piston is released by spring tension and hydraulic
pressure.
The accumulator controls the hydraulic pressure
on the apply side of the kickdown servo during the
1-2 upshift; thereby, cushioning the kickdown band
application at any throttle position.
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