1999 DODGE NEON Service Repair Manual

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 the 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:
²Pressure supply system
²Pressure regulating valves
²Flow control valves
²Clutches
²Band 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 hydraulic
and lubrication requirements.Oil pump housing
assemblies are available with preselected 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.
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 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 bypass 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.
AUTOMATIC TRANSMISSION SHIFTER/IGNITION
INTERLOCK
The Shifter/Ignition Interlock, is a mechanical
cable operated system (Fig. 1). It interconnects the
automatic transmission floor±mounted shifter to the
steering column ignition switch. The interlock system
locks the floor±mounted shift lever into the PARK
position whenever the ignition switch is in the LOCK
or ACCESSORY position. When the key is in the
OFF or RUN position, the shifter is unlocked and
will move into any position. Also the interlock system
prevents the ignition switch from being turned to
LOCK or ACCESSORY position, unless shifter is in
the PARK position.
GEARSHIFT AND PARKING LOCK CONTROLS
The transaxle is controlled by alever typegear-
shift incorporated within the console. The control has
21 - 42 TRANSAXLEPL
GENERAL INFORMATION (Continued)

six selector lever positions: P (Park), R (Reverse), N
(Neutral), and D (Drive), 2 (Second), and 1 (First).
The parking lock is applied by moving the selector
lever past a gate to the (P) position.Do not apply
the parking lock until the vehicle has stopped;
otherwise, a severe banging noise will occur.
TORQUE CONVERTER CLUTCH SOLENOID WIRING
CONNECTOR
If the solenoid wiring connector is unplugged, the
torque converter will not engage (Fig. 2).
GOVERNOR
The governor can be serviced by removing the
transaxle oil pan and valve body assembly. The gov-
ernor can be unbolted from the governor support and
removed from the transaxle for reconditioning or
replacement.
When cleaning or assembling the governor, be sure
the governor valves move freely in the bores of the
governor body.
DIAGNOSIS AND TESTING
THREE SPEED TRANSAXLE DIAGNOSIS AND
TESTS
Automatic transaxle malfunctions may be caused
by four general conditions:
(1) Poor engine performance
(2) Improper adjustments
(3) Hydraulic malfunctions
(4) Mechanical malfunctions
Diagnosis of these problems should always begin
by checking the easily accessible variables; fluid level
and condition, gearshift cable adjustment, and throt-
tle pressure cable adjustment. Then perform a road
test to determine if the problem has been corrected
or that more diagnosis is necessary. If the problem
exists after the preliminary tests and corrections are
completed, hydraulic pressure tests should be per-
formed
31TH HYDRAULIC TROUBLE CODE CHARTS
The following charts should be used to help diag-
nose hydraulic or mechanical faults in the transaxle.
Fig. 1 Shifter Ignition Interlock System Components
Fig. 2 Torque Converter Clutch Solenoid Wiring
Connector
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DESCRIPTION AND OPERATION (Continued)

Diagnosis Guide
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DIAGNOSIS AND TESTING (Continued)

Diagnosis Guide
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DIAGNOSIS AND TESTING (Continued)

Diagnosis Guide
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DIAGNOSIS AND TESTING (Continued)

Diagnosis Guide
PLTRANSAXLE 21 - 47
DIAGNOSIS AND TESTING (Continued)

Diagnosis Guide
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DIAGNOSIS AND TESTING (Continued)

Diagnosis Guide
PLTRANSAXLE 21 - 49
DIAGNOSIS AND TESTING (Continued)