Page 3241 of 4284

ing state. The result is an apply or release of a fric-
tional element.
The 2/4 and UD solenoids are normally applied,
which by design allow fluid to pass through in their
relaxed or ªoffº state. This allows transaxle limp-in
(P,R,N,2) in the event of an electrical failure.
The continuity of the solenoids and circuits are
periodically tested. Each solenoid is turned on or off
depending on its current state. An inductive spike
should be detected by the TCM during this test. It no
spike is detected, the circuit is tested again to verify
the failure. In addition to the periodic testing, the
solenoid circuits are tested if a speed ratio or pres-
sure switch error occurs.
PRESSURE SWITCHES
The TCM relies on three pressure switches to mon-
itor fluid pressure in the L/R, 2/4, and OD hydraulic
circuits. The primary purpose of these switches is to
help the TCM detect when clutch circuit hydraulic
failures occur. The range for the pressure switch clos-
ing and opening points is 11-23 psi. Typically the
switch opening point will be approximately one psi
lower than the closing point. For example, a switch
may close at 18 psi and open at 17 psi. The switches
are continuously monitored by the TCM for the cor-
rect states (open or closed) in each gear as shown in
the following chart:
PRESSURE SWITCH STATES
GEAR L/R 2/4 OD
ROPOPOP
P/N CL OP OP
1st CL OP OP
2nd OP CL OP
DOPOPCL
OD OP CL CL
OP = OPEN
CL = CLOSED
A Diagnostic Trouble Code (DTC) will set if the
TCM senses any switch open or closed at the wrong
time in a given gear.
The TCM also tests the 2/4 and OD pressure
switches when they are normally off (OD and 2/4 are
tested in 1st gear, OD in 2nd gear, and 2/4 in 3rd
gear). The test simply verifies that they are opera-
tional, by looking for a closed state when the corre-
sponding element is applied. Immediately after a
shift into 1st, 2nd, or 3rd gear with the engine speed
above 1000 rpm, the TCM momentarily turns on ele-
ment pressure to the 2/4 and/or OD clutch circuits to
identify that the appropriate switch has closed. If it
doesn't close, it is tested again. If the switch fails toclose the second time, the appropriate Diagnostic
Trouble Code (DTC) will set.
REMOVAL
NOTE: If solenoid/pressure switch assembly is
being replaced, it is necessary to perform the TCM
Quick Learn Procedure. (Refer to 8 - ELECTRICAL/
ELECTRONIC CONTROL MODULES/TRANSMISSION
CONTROL MODULE - STANDARD PROCEDURE)
(1) Disconnect battery negative cable.
(2) Remove air cleaner assembly.
(3) Disconnect solenoid/pressure switch assembly
connector.
(4) Disconnect input speed sensor connector.
(5) Remove input speed sensor (Fig. 318).
(6) Remove three (3) solenoid/pressure switch
assembly-to-transaxle case bolts (Fig. 319).
(7) Remove solenoid/pressure switch assembly and
gasket (Fig. 320). Use care to prevent gasket mate-
rial and foreign objects from become lodged in the
transaxle case ports.
INSTALLATION
NOTE: If solenoid/pressure switch assembly is
being replaced, it is necessary to perform the TCM
Quick Learn Procedure. (Refer to 8 - ELECTRICAL/
ELECTRONIC CONTROL MODULES/TRANSMISSION
CONTROL MODULE - STANDARD PROCEDURE)
(1) Install solenoid/pressure switch assembly and
new gasket to transaxle (Fig. 320).
Fig. 318 Input Speed Sensor
1 - INPUT SPEED SENSOR
RSAUTOMATIC - 41TE21 - 277
SOLENOID/PRESSURE SWITCH ASSY (Continued)
Page 3242 of 4284

(2) Install and torque three (3) bolts (Fig. 319) to
13 N´m (110 in. lbs.).
(3) Install input speed sensor (Fig. 318) and torque
to 27 N´m (20 ft. lbs.).
(4) Connect input speed sensor connector.(5) Install solenoid/pressure switch 8-way connec-
tor and torque to 4 N´m (35 in. lbs.).
(6) Install air cleaner assembly.
(7) Connect battery negative cable.
(8) If solenoid/pressure switch assembly was
replaced, perform TCM Quick Learn procedure.
(Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/TRANSMISSION CONTROL
MODULE - STANDARD PROCEDURE)
SPEED SENSOR - INPUT
DESCRIPTION
The Input Speed Sensor is a two-wire magnetic
pickup device that generates AC signals as rotation
occurs. It is threaded into the transaxle case (Fig.
321) , sealed with an o-ring (Fig. 322), and is consid-
ered a primary input to the Transmission Control
Module (TCM).
OPERATION
The Input Speed Sensor provides information on
how fast the input shaft is rotating. As the teeth of
the input clutch hub pass by the sensor coil (Fig.
323) , an AC voltage is generated and sent to the
TCM. The TCM interprets this information as input
shaft rpm.
The TCM compares the input speed signal with
output speed signal to determine the following:
²Transmission gear ratio
²Speed ratio error detection
²CVI calculation
Fig. 319 Solenoid/Pressure Switch Assembly-to-
Case Bolts
1 - BOLTS
2 - SOLENOID AND PRESSURE SWITCH ASSEMBLY
Fig. 320 Solenoid/Pressure Switch Assembly and
Gasket
1 - SOLENOID/PRESSURE SWITCH ASSEMBLY
2 - GASKET
Fig. 321 Input Speed Sensor Location
1 - INPUT SPEED SENSOR
21 - 278 AUTOMATIC - 41TERS
SOLENOID/PRESSURE SWITCH ASSY (Continued)
Page 3243 of 4284

The TCM also compares the input speed signal and
the engine speed signal to determine the following:
²Torque converter clutch slippage
²Torque converter element speed ratio
REMOVAL
(1) Disconnect battery negative cable.
(2) If necessary, disconnect and cap off transmis-
sion oil cooler lines.(3) Disconnect input speed sensor connector.
(4) Unscrew and remove input speed sensor (Fig.
324).
(5) Inspect speed sensor o-ring (Fig. 325) and
replace if necessary.
INSTALLATION
(1) Verify o-ring is installed into position.
(2) Install and tighten input speed sensor to 27
N´m (20 ft. lbs.).
(3) Connect speed sensor connector.
(4) Connect battery negative cable.
Fig. 322 O-Ring Location
1 - INPUT SPEED SENSOR
2 - O-RING
Fig. 323 Sensor Relation to Input Clutch Hub
1 - INPUT SPEED SENSOR
2 - TRANSAXLE CASE
3 - INPUT CLUTCH HUB
Fig. 324 Input (Turbine) Speed Sensor
1 - INPUT SPEED SENSOR
Fig. 325 O-ring Location
1 - INPUT SPEED SENSOR
2 - O-RING
RSAUTOMATIC - 41TE21 - 279
SPEED SENSOR - INPUT (Continued)
Page 3244 of 4284

SPEED SENSOR - OUTPUT
DESCRIPTION
The Output Speed Sensor is a two-wire magnetic
pickup device that generates an AC signal as rotation
occurs. It is threaded into the transaxle case (Fig.
326) , sealed with an o-ring (Fig. 327), and is consid-
ered a primary input to the Transmission Control
Module (TCM).
OPERATION
The Output Speed Sensor provides information on
how fast the output shaft is rotating. As the rear
planetary carrier park pawl lugs pass by the sensor
coil (Fig. 328) , an AC voltage is generated and sent
to the TCM. The TCM interprets this information as
output shaft rpm.
The TCM compares the input and output speed
signals to determine the following:
²Transmission gear ratio
²Speed ratio error detection
²CVI calculation
VEHICLE SPEED SIGNAL
The vehicle speed signal is taken from the Output
Speed Sensor. The TCM converts this signal into a
pulse per mile signal and sends it to the PCM. The
PCM, in turn, sends the vehicle speed message
across the communication bus to the BCM. The BCM
sends this signal to the Instrument Cluster to dis-
play vehicle speed to the driver. The vehicle speed
signal pulse is roughly 8000 pulses per mile.
REMOVAL
(1) Disconnect battery negative cable.
(2) Raise vehicle on hoist.
(3) Disconnect output speed sensor connector.
(4) Unscrew and remove output speed sensor (Fig.
329).
(5) Inspect speed sensor o-ring (Fig. 330) and
replace if necessary.
Fig. 326 Output Speed Sensor
1 - OUTPUT SPEED SENSOR
Fig. 327 O-Ring Location
1 - OUTPUT SPEED SENSOR
2 - O-RING
Fig. 328 Sensor Relation to Planet Carrier Park Pawl
1 - OUTPUT SPEED SENSOR
2 - REAR PLANET CARRIER/OUTPUT SHAFT ASSEMBLY
3 - TRANSAXLE CASE
21 - 280 AUTOMATIC - 41TERS
Page 3245 of 4284

INSTALLATION
(1) Verify o-ring is installed into position (Fig.
330).
(2) Install and tighten input speed sensor to 27
N´m (20 ft. lbs.).
(3) Connect speed sensor connector.
(4) Connect battery negative cable.
TORQUE CONVERTER
DESCRIPTION
The torque converter (Fig. 331) is a hydraulic
device that couples the engine crankshaft to the
transmission. The torque converter consists of an
outer shell with an internal turbine, a stator, an
overrunning clutch, an impeller and an electronically
applied converter clutch. The converter clutch pro-
vides reduced engine speed and greater fuel economy
when engaged. Clutch engagement also provides
reduced transmission fluid temperatures. The con-
verter clutch engages in third gear. The torque con-
verter hub drives the transmission oil (fluid) pump.
The torque converter is a sealed, welded unit that
is not repairable and is serviced as an assembly.
CAUTION: The torque converter must be replaced if
a transmission failure resulted in large amounts of
metal or fiber contamination in the fluid. If the fluid
is contaminated, flush the fluid cooler and lines.
Fig. 329 Output Speed Sensor
1 - OUTPUT SPEED SENSOR
Fig. 330 O-ring Location
1 - OUTPUT SPEED SENSOR
2 - O-RING
Fig. 331 Torque Converter Assembly
1 - TURBINE
2 - IMPELLER
3 - HUB
4-STATOR
5 - CONVERTER CLUTCH DISC
6 - DRIVE PLATE
RSAUTOMATIC - 41TE21 - 281
SPEED SENSOR - OUTPUT (Continued)
Page 3246 of 4284

IMPELLER
The impeller (Fig. 332) is an integral part of the
converter housing. The impeller consists of curved
blades placed radially along the inside of the housing
on the transmission side of the converter. As the con-
verter housing is rotated by the engine, so is the
impeller, because they are one and the same and are
the driving member of the system.
TURBINE
The turbine (Fig. 333) is the output, or driven,
member of the converter. The turbine is mounted
within the housing opposite the impeller, but is not
attached to the housing. The input shaft is inserted
through the center of the impeller and splined into
the turbine. The design of the turbine is similar to
the impeller, except the blades of the turbine are
curved in the opposite direction.
Fig. 332 Impeller
1 - ENGINE FLEXPLATE
2 - OIL FLOW FROM IMPELLER SECTION INTO TURBINE
SECTION
3 - IMPELLER VANES AND COVER ARE INTEGRAL4 - ENGINE ROTATION
5 - ENGINE ROTATION
21 - 282 AUTOMATIC - 41TERS
TORQUE CONVERTER (Continued)
Page 3247 of 4284

STATOR
The stator assembly (Fig. 334) is mounted on a sta-
tionary shaft which is an integral part of the oil
pump. The stator is located between the impeller and
turbine within the torque converter case (Fig. 335).
The stator contains an over-running clutch, which
allows the stator to rotate only in a clockwise direc-
tion. When the stator is locked against the over-run-
ning clutch, the torque multiplication feature of the
torque converter is operational.
TORQUE CONVERTER CLUTCH (TCC)
The TCC (Fig. 336) was installed to improve the
efficiency of the torque converter that is lost to the
slippage of the fluid coupling. Although the fluid cou-
pling provides smooth, shock±free power transfer, it
is natural for all fluid couplings to slip. If the impel-
ler and turbine were mechanically locked together, a
zero slippage condition could be obtained. A hydraulic
piston was added to the turbine, and a friction mate-
rial was added to the inside of the front cover to pro-
vide this mechanical lock-up.
Fig. 333 Turbine
1 - TURBINE VANE
2 - ENGINE ROTATION
3 - INPUT SHAFT
4 - PORTION OF TORQUE CONVERTER COVER5 - ENGINE ROTATION
6 - OIL FLOW WITHIN TURBINE SECTION
RSAUTOMATIC - 41TE21 - 283
TORQUE CONVERTER (Continued)
Page 3248 of 4284

OPERATION
The converter impeller (Fig. 337) (driving member),
which is integral to the converter housing and bolted
to the engine drive plate, rotates at engine speed.
The converter turbine (driven member), which reacts
from fluid pressure generated by the impeller, rotates
and turns the transmission input shaft.
TURBINE
As the fluid that was put into motion by the impel-
ler blades strikes the blades of the turbine, some of
the energy and rotational force is transferred into the
turbine and the input shaft. This causes both of them
(turbine and input shaft) to rotate in a clockwise
direction following the impeller. As the fluid is leav-
ing the trailing edges of the turbine's blades it con-
tinues in a ªhinderingº direction back toward the
impeller. If the fluid is not redirected before it strikes
the impeller, it will strike the impeller in such a
direction that it would tend to slow it down.
Fig. 334 Stator Components
1 - CAM (OUTER RACE)
2 - ROLLER
3 - SPRING
4 - INNER RACE
Fig. 335 Stator Location
1-STATOR
2 - IMPELLER
3 - FLUID FLOW
4 - TURBINE
Fig. 336 Torque Converter Clutch (TCC)
1 - IMPELLER FRONT COVER
2 - THRUST WASHER ASSEMBLY
3 - IMPELLER
4-STATOR
5 - TURBINE
6 - PISTON
7 - FRICTION DISC
21 - 284 AUTOMATIC - 41TERS
TORQUE CONVERTER (Continued)