Chrysler Town, Dodge Caravan. Manual - part 422

PRESSURE SWITCHES

The PCM/TCM relies on three pressure switches to

monitor fluid pressure in the L/R, 2/4, and OD
hydraulic circuits. The primary purpose of these
switches is to help the PCM/TCM detect when clutch
circuit hydraulic failures occur. The range for the
pressure switch closing 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 PCM/TCM for the correct states (open or
closed) in each gear as shown in the following chart:

PRESSURE SWITCH STATES

GEAR

L/R

2/4

P/N

1st

2nd

OP = OPEN

CL = CLOSED

A Diagnostic Trouble Code (DTC) will set if the

PCM/TCM senses any switch open or closed at the
wrong time in a given gear.

The PCM/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 PCM/TCM momentarily turns
on element pressure to the 2/4 and/or OD clutch cir-
cuits to identify that the appropriate switch has
closed. If it doesn’t close, it is tested again. If the
switch fails to close 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. 305).

(6) Remove

three

(3)

solenoid/pressure

switch

assembly-to-transaxle case bolts (Fig. 306).

(7) Remove solenoid/pressure switch assembly and

gasket (Fig. 307). Use care to prevent gasket mate-
rial and foreign objects from become lodged in the
transaxle case ports.

Fig. 305 Input Speed Sensor

1 - INPUT SPEED SENSOR

Fig. 306 Solenoid/Pressure Switch Assembly-to-

Case Bolts

1 - BOLTS
2 - SOLENOID AND PRESSURE SWITCH ASSEMBLY

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41TE AUTOMATIC TRANSAXLE

SOLENOID/PRESSURE SWITCH ASSY (Continued)

INSTALLATION

(1) Install solenoid/pressure switch assembly and

new gasket to transaxle (Fig. 307).

(2) Install and torque three (3) bolts (Fig. 306) to

13 N·m (110 in. lbs.).

(3) Install input speed sensor (Fig. 305) 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.
308), sealed with an o-ring (Fig. 309), and is consid-
ered a primary input to the Powertrain/Transmission
Control Module.

Fig. 307 Solenoid/Pressure Switch Assembly and

Gasket

1 - SOLENOID/PRESSURE SWITCH ASSEMBLY
2 - GASKET

Fig. 308 Input Speed Sensor Location

1 - INPUT SPEED SENSOR

Fig. 309 O-Ring Location

1 - INPUT SPEED SENSOR
2 - O-RING

41TE AUTOMATIC TRANSAXLE

21 - 239

SOLENOID/PRESSURE SWITCH ASSY (Continued)

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.
310), an AC voltage is generated and sent to the
PCM/TCM. The PCM/TCM interprets this informa-
tion as input shaft rpm.

The PCM/TCM compares the input speed signal

with output speed signal to determine the following:

• Transmission gear ratio

• Speed ratio error detection

• CVI calculation
The PCM/TCM also compares the input speed sig-

nal and the engine speed signal to determine the fol-
lowing:

• Torque converter clutch slippage

• Torque 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.

311).

(5) Inspect speed sensor o-ring (Fig. 312) 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. 310 Sensor Relation to Input Clutch Hub

1 - INPUT SPEED SENSOR
2 - TRANSAXLE CASE
3 - INPUT CLUTCH HUB

Fig. 311 Input (Turbine) Speed Sensor

1 - INPUT SPEED SENSOR

Fig. 312 O-ring Location

1 - INPUT SPEED SENSOR
2 - O-RING

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41TE AUTOMATIC TRANSAXLE

SPEED SENSOR - INPUT (Continued)

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.
313), sealed with an o-ring (Fig. 314), and is consid-
ered a primary input to the Powetrain/Transmission
Control Module.

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. 315), an AC voltage is generated and sent to
the PCM/TCM. The PCM/TCM interprets this infor-
mation as output shaft rpm.

The PCM/TCM compares the input and output

speed signals to determine the following:

• Transmission gear ratio

• Speed ratio error detection

• CVI calculation

VEHICLE SPEED SIGNAL

The vehicle speed signal is taken from the Output

Speed Sensor. The PCM converts this signal into a
pulse per mile signal and sends the vehicle speed
message across the communication bus to the BCM.
The BCM sends this signal to the Instrument Cluster
to display 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.

316).

(5) Inspect speed sensor o-ring (Fig. 317) and

replace if necessary.

Fig. 313 Output Speed Sensor

1 - OUTPUT SPEED SENSOR

Fig. 314 O-Ring Location

1 - OUTPUT SPEED SENSOR
2 - O-RING

Fig. 315 Sensor Relation to Planet Carrier Park Pawl

1 - OUTPUT SPEED SENSOR
2 - REAR PLANET CARRIER/OUTPUT SHAFT ASSEMBLY
3 - TRANSAXLE CASE

41TE AUTOMATIC TRANSAXLE

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