Chrysler Town & Country/Voyager, Dodge Caravan, Plymouth Voyager. Manual — part 83
If end play is too high, install a .05 mm (.002
inch) thinner shim combination. If end play is
too low, install a .05 mm (.002 inch) thicker shim
combination. Repeat until .05 to .25 mm (.002 to
.010 inch) end play is obtained.
TRANSFER BEARING SHIM CHART
BEARING SHIM CHART
.
TRANSAXLE
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4-SPEED ELECTRONIC AUTOMATIC TRANSAXLE
INDEX
page
page
Aluminum Thread Repair
. . . . . . . . . . . . . . . . . . . 95
Bearing Adjustment Procedures
. . . . . . . . . . . . . 137
Clutch Air Pressure Tests
. . . . . . . . . . . . . . . . . . . 92
Determining No. 4 Thrust Plate Thickness
(Input Shaft End Play)
. . . . . . . . . . . . . . . . . . . 115
Differential Repair
. . . . . . . . . . . . . . . . . . . . . . . 132
Distance Sensor Gear
. . . . . . . . . . . . . . . . . . . . . 95
Fluid and Filter Change
. . . . . . . . . . . . . . . . . . . . 89
Fluid Drain and Refill
. . . . . . . . . . . . . . . . . . . . . . 89
Fluid Leakage-Transaxle Torque Converter Housing
Area
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Fluid Level and Condition
. . . . . . . . . . . . . . . . . . . 89
Gearshift Linkage Adjustment
. . . . . . . . . . . . . . . . 94
General Diagnosis
. . . . . . . . . . . . . . . . . . . . . . . . 85
General Information
. . . . . . . . . . . . . . . . . . . . . . . . 1
Hydraulic Pressure Tests
. . . . . . . . . . . . . . . . . . . 91
Input Clutches-Recondition
. . . . . . . . . . . . . . . . . 116
Neutral Safety Switch
. . . . . . . . . . . . . . . . . . . . . . 99
Oil Cooler Flow Check
. . . . . . . . . . . . . . . . . . . . . 95
Oil Coolers and Tubes Reverse Flushing
. . . . . . . 95
Oil Pump Seal-Replace
. . . . . . . . . . . . . . . . . . . 132
PRNDL Switch
. . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Road Test
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Selection of Lubricant
. . . . . . . . . . . . . . . . . . . . . . 89
Solenoid Assembly-Replace
. . . . . . . . . . . . . . . . . 98
Special Additives
. . . . . . . . . . . . . . . . . . . . . . . . . 89
Speed Sensor-Input
. . . . . . . . . . . . . . . . . . . . . . . 99
Speed Sensor-Output
. . . . . . . . . . . . . . . . . . . . . . 99
Transaxle Removal and Installation . . . . . . . . . . . . 96
Transaxle-Recondition
. . . . . . . . . . . . . . . . . . . . 100
Valve Body-Recondition
. . . . . . . . . . . . . . . . . . . 128
GENERAL INFORMATION
This electronic four-speed FWD transaxle is the first
use of fully-adaptive controls in a production automo-
tive transaxle. Adaptive controls are those which per-
form their functions based on real-time feedback sen-
sor information, just as is done by electronic anti-lock
brake controls. The transaxle is conventional in that it
uses hydraulically-applied clutches to shift a planetary
gear train, its uses electronics to control virtually all
functions.
TRANSAXLE IDENTIFICATION
The transaxle identification code is printed on a
label. The label is located on the transaxle case next to
the solenoid assembly (Fig. 1).
Refer to Figure 2 for an internal view of the transaxle
assembly.
OPERATION
The transaxle provides forward ratios of 2.84, 1.57,
1.00, and 0.69 with torque converter lockup available
in 2nd, direct, or overdrive gear; the Reverse ratio is
2.21. The shift lever is conventional with six positions:
P, R, N, OD, 3, and L. When OD is selected the
transaxle shifts normally through all four speeds with
lockup in overdrive; this position is recommended for
most driving. The 3 position is tailored for use in hilly
or mountainous driving. When 3 is selected, the trans-
mission uses only 1st, 2nd, and direct gears with
2nd-direct shift delayed to 40 mph or greater. When
operating in 3 or L positions torque converter lockup
occurs in direct gear for improved transmission cooling
when towing trailers and on steep grades. If high
engine coolant temperature occurs, the torque con-
verter will also lock up in 2nd gear. The L position
provides maximum engine braking for descending
steep grades. Unlike most current transaxles, upshifts
are provided to 2nd or direct gear at peak engine
speeds if the accelerator is depressed. This provides
engine over-speed protection and maximum perfor-
mance.
Fig. 1 Identification Tag Location
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TRANSAXLE
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Fig.
2
Internal
V
iew
of
T
ransaxle
.
TRANSAXLE
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CLUTCH AND GEAR
The 4-speed electronic transaxle consists of:
• Three multiple-disc input clutches
• Two multiple disc grounded clutches
• Four hydraulic accumulators
• Two planetary gear sets
This provides four forward ratios and a reverse ratio.
The clutch-apply pistons were designed with centrifu-
gally balanced oil cavities so that quick response and
good control can be achieved at any speed. A push/pull
piston is incorporated for two of the three input
clutches.
CAUTION: Some clutch packs appear similar, but
they are not the same. Do not interchange clutch
components as they might fail.
HYDRAULICS
The hydraulics of the new transaxle provide the
manual shift lever select function, main line pressure
regulation, and torque converter and cooler flow con-
trol. Oil flow to the friction elements is controlled
directly by four solenoid valves. The hydraulics also
include a unique logic-controlled ‘‘solenoid lock-up con-
trol valve’’. This valve locks out the 1st gear reaction
element with the application of 2nd, direct, or over-
drive gear elements. It also redirects the 1st gear
solenoid output so that it can control torque converter
lockup operation. To regain access to 1st gear, a special
sequence of solenoid commands must be used to unlock
and move the solenoid lock-up control valve. This
precludes any application of the 1st gear reaction
element with other elements applied, unless specifi-
cally commanded the controller. It also allows one
solenoid to control two friction elements.
Small, high-rate accumulators are provided in each
controlled friction element circuit. These serve to ab-
sorb the pressure responses, and allow the controls to
read and respond to changes that are occurring.
SOLENOIDS
Since the solenoid valves perform virtually all con-
trol functions, these valves must be extremely durable
and tolerant of normal dirt particles. For that reason
hardened-steel poppet and ball valves are used. These
are free from any close operating clearances, and the
solenoids operate the valves directly without any inter-
mediate element. Direct operation means that these
units must have very high output so that they can close
against the sizeable flow areas and high line pressures.
Fast response is also required to meet the control
requirements.
Two of the solenoids are normally-venting and two
are normally-applying; this was done to provide a
default mode of operation. With no electrical power, the
transmission provides 2nd gear in ‘‘OD,’’ ‘‘3,’’ or ‘‘L’’ shift
lever positions. All other shift lever positions will
function normally. The choice of 2nd gear was made to
provide adequate performance while still accommodat-
ing highway speeds.
SENSORS
There are three pressure switches to identify sole-
noid application and two speed sensors to read input
(torque converter turbine) and output (parking sprag)
speeds. There is also a position switch to indicate the
manual shift lever position. The pressure switches are
incorporated in an assembly with the solenoids. Engine
speed, throttle position, temperature, etc., are also
observed. Some of these signals are read directly from
the engine control sensors; others are read from a
multiplex circuit with the engine controller.
ELECTRONICS
The electronic control unit is located underhood in a
potted, die cast aluminum housing with a sealed,
60-way connector.
ADAPTIVE CONTROLS
These controls function by reading the input and
output speeds over 140 times a second and responding
to each new reading. This provides the precise and
sophisticated friction element control needed to make
smooth clutch-to-clutch shifts for all gear changes. As
with most automatic transaxles, all shifts involve re-
leasing one element and applying a different element.
In simplified terms, the upshift logic allows the releas-
ing element to slip back wards slightly to ensure that it
does not have excess capacity; the apply element is
filled until it begins to make the speed change to the
higher gear; its apply pressure is then controlled to
maintain the desired rate of speed change until the
shift is complete. The key to providing excellent shift
quality is precision; for example, as mentioned, the
release element for upshifts is allowed to slip back-
wards slightly; the amount of that slip is typically less
than a total of 20 degrees. To achieve that precision,
the controller learns the characteristics of the
particular transaxle that it is controlling. It
learns the release rate of the releasing element
and the apply time of the applying element. It
also learns the rate at which the apply element
builds pressure sufficient to begin making the
speed change. This method achieves more precision
than would be possible with exacting tolerances. It can
also adapt to any changes that occur with age or
environment, for example, altitude, temperature, en-
gine output, etc.
For kickdown shifts, the control logic allows the
releasing element to slip and then controls the rate at
which the input (and engine) accelerate; when the
lower gear speed is achieved, the releasing element
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TRANSAXLE
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