Engine DODGE TOWN AND COUNTRY 2001 Service Manual

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)
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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)
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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)
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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)
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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)
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STATOR
Torque multiplication is achieved by locking the
stator's over-running clutch to its shaft (Fig. 338).
Under stall conditions (the turbine is stationary), the
oil leaving the turbine blades strikes the face of the
stator blades and tries to rotate them in a counter-
clockwise direction. When this happens the over±run-
ning clutch of the stator locks and holds the stator
from rotating. With the stator locked, the oil strikes
the stator blades and is redirected into a ªhelpingº
direction before it enters the impeller. This circula-
tion of oil from impeller to turbine, turbine to stator,
and stator to impeller, can produce a maximum
torque multiplication of about 2.4:1. As the turbine
begins to match the speed of the impeller, the fluid
that was hitting the stator in such as way as to
cause it to lock±up is no longer doing so. In this con-
dition of operation, the stator begins to free wheel
and the converter acts as a fluid coupling.
TORQUE CONVERTER CLUTCH (TCC)
In a standard torque converter, the impeller and
turbine are rotating at about the same speed and the
stator is freewheeling, providing no torque multipli-
cation. By applying the turbine's piston to the front
cover's friction material, a total converter engage-ment can be obtained. The result of this engagement
is a direct 1:1 mechanical link between the engine
and the transmission.
Fig. 337 Torque Converter Fluid Operation
1 - APPLY PRESSURE
2 - THE PISTON MOVES SLIGHTLY FORWARD3 - RELEASE PRESSURE
4 - THE PISTON MOVES SLIGHTLY REARWARD
Fig. 338 Stator Operation
1 - DIRECTION STATOR WILL FREE WHEEL DUE TO OIL
PUSHING ON BACKSIDE OF VANES
2 - FRONT OF ENGINE
3 - INCREASED ANGLE AS OIL STRIKES VANES
4 - DIRECTION STATOR IS LOCKED UP DUE TO OIL PUSHING
AGAINST STATOR VANES
RSAUTOMATIC - 41TE21 - 285
TORQUE CONVERTER (Continued)
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TRANSMISSION CONTROL
RELAY
DESCRIPTION
The transmission control relay (Fig. 340) is located
in the Intelligent Power Module (IPM), which is
located on the left side of the engine compartment
between the battery and left fender.
OPERATION
The relay is supplied fused B+ voltage, energized
by the TCM, and is used to supply power to the sole-
noid pack when the transmission is in normal oper-
ating mode. When the relay is ªoffº, no power is
supplied to the solenoid pack and the transmission is
in ªlimp-inº mode. After a controller reset (ignition
key turned to the ªrunº position or after cranking
engine), the TCM energizes the relay. Prior to this,
the TCM verifies that the contacts are open by check-
ing for no voltage at the switched battery terminals.
After this is verified, the voltage at the solenoid pack
pressure switches is checked. After the relay is ener-
gized, the TCM monitors the terminals to verify that
the voltage is greater than 3 volts.
TRANSMISSION RANGE
SENSOR
DESCRIPTION
The Transmission Range Sensor (TRS) is mounted
to the top of the valve body inside the transaxle and
can only be serviced by removing the valve body. The
electrical connector extends through the transaxle
case (Fig. 341) .
The Transmission Range Sensor (TRS) has four
switch contacts that monitor shift lever position and
send the information to the TCM.
The TRS also has an integrated temperature sen-
sor (thermistor) that communicates transaxle tem-
perature to the TCM and PCM (Fig. 342) .
OPERATION
The Transmission Range Sensor (TRS) (Fig. 341)
communicates shift lever position (SLP) to the TCM
as a combination of open and closed switches. Each
shift lever position has an assigned combination of
switch states (open/closed) that the TCM receives
from four sense circuits. The TCM interprets this
information and determines the appropriate trans-
axle gear position and shift schedule.
Fig. 340 Transmission Control Relay Location
1 - TRANSMISSION CONTROL RELAY
2 - LEFT FENDER
3 - INTELLIGENT POWER MODULE (IPM)
4 - BATTERYFig. 341 Transmission Range Sensor (TRS)
Location
1 - TRANSMISSION RANGE SENSOR
RSAUTOMATIC - 41TE21 - 287
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Since there are four switches, there are 16 possible
combinations of open and closed switches (codes).
Seven of these codes are related to gear position and
three are recognized as ªbetween gearº codes. This
results in six codes which should never occur. These
are called ªinvalidº codes. An invalid code will result
in a DTC, and the TCM will then determine the shift
lever position based on pressure switch data. This
allows reasonably normal transmission operation
with a TRS failure.
TRS SWITCH STATES
SLP T42 T41 T3 T1
PCL CL CL OP
RCL OP OP OP
NCL CL OP CL
ODOP OP OP CL
3OP OP CL OP
LCL OP CL CL
TRANSMISSION TEMPERATURE SENSOR
The TRS has an integrated thermistor (Fig. 342)
that the TCM uses to monitor the transmission's
sump temperature. Since fluid temperature can
affect transmission shift quality and convertor lock
up, the TCM requires this information to determine
which shift schedule to operate in. The PCM also
monitors this temperature data so it can energize the
vehicle cooling fan(s) when a transmission ªoverheatº
condition exists. If the thermistor circuit fails, the
TCM will revert to calculated oil temperature usage.
CALCULATED TEMPERATURE
A failure in the temperature sensor or circuit will
result in calculated temperature being substituted for
actual temperature. Calculated temperature is a pre-
dicted fluid temperature which is calculated from a
combination of inputs:
²Battery (ambient) temperature
²Engine coolant temperature
²In-gear run time since start-up
REMOVAL
(1) Remove valve body assembly from transaxle.
(Refer to 21 - TRANSMISSION/TRANSAXLE/AUTO-
MATIC - 41TE/VALVE BODY - REMOVAL)
(2) Remove transmission range sensor retaining
screw and remove sensor from valve body (Fig. 343).
(3) Remove TRS from manual shaft.
INSTALLATION
(1) Install transmission range sensor (TRS) to the
valve body and torque retaining screw (Fig. 343) to 5
N´m (45 in. lbs.).
(2) Install valve body to transaxle. (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC -
41TE/VALVE BODY - INSTALLATION)
Fig. 342 Transmission Temperature Sensor
1 - TRANSMISSION RANGE SENSOR
2 - TEMPERATURE SENSOR
Fig. 343 Remove Transmission Range Sensor
1 - TRANSMISSION RANGE SENSOR
2 - MANUAL VALVE CONTROL PIN
3 - RETAINING SCREW
21 - 288 AUTOMATIC - 41TERS
TRANSMISSION RANGE SENSOR (Continued)
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TORQUE REDUCTION LINK
(TRD)
DESCRIPTION
The Torque Reduction Link (TRD) is a wire
between the PCM and TCM that is used by the TCM
to request torque management. Torque management
controls or reduces torque output of the engine dur-
ing certain shift sequences, reducing torque applied
to the transaxle clutches.
OPERATION
The torque management signal is basically a
12-volt pull-up supplied by the PCM to the TCM over
the torque reduction link (TRD). Torque management
is requested when the TCM pulses this signal to
ground. The PCM recognizes this request and
responds by retarding ignition timing, killing fuel
injectors, etc. The PCM sends a confirmation of the
request to the TCM via the communication bus.
Torque reduction is not noticable by the driver, and
usually lasts for a very short period of time.
If the confirmation signal is not received by the
TCM after two sequential request messages, a diag-
nostic trouble code will be set.
VALVE BODY
DESCRIPTION
The valve body assembly consists of a cast alumi-
num valve body, a separator plate, and transfer
plate. The valve body contains valves and check balls
that control fluid delivery to the torque converter
clutch, solenoid/pressure switch assembly, and fric-
tional clutches. The valve body contains the following
components (Fig. 344):
²Regulator valve
²Solenoid switch valve
²Manual valve
²Converter clutch switch valve
²Converter clutch control valve
²Torque converter regulator valve
²Low/Reverse switch valve
In addition, the valve body also contains the ther-
mal valve, #2,3&4 check balls, the #5 (overdrive)
check valve and the 2/4 accumulator assembly. (Refer
to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC
- 41TE/VALVE BODY - DISASSEMBLY)
Fig. 344 Valve Body Assembly
1 - VALVE BODY
2 - T/C REGULATOR VALVE
3 - L/R SWITCH VALVE
4 - CONVERTER CLUTCH CONTROL VALVE
5 - MANUAL VALVE6 - CONVERTER CLUTCH SWITCH VALVE
7 - SOLENOID SWITCH VALVE
8 - REGULATOR VALVE
RSAUTOMATIC - 41TE21 - 289
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The NV T850 5-speed transaxle (Fig. 1) is a con-
stant-mesh manual transaxle that is synchronized in
all gear ranges, including reverse.
The transaxle consists of three major sub-assem-
blies: the input shaft, intermediate shaft, and differ-
ential assembly. The transaxle shift system consists
of a mechanical shift cover, rails, forks, and cables.
The unique design of this shift system provides a
higher mechanical advantage, resulting in less fric-
tion and lower shift cable loads for smoother, more
positive operation.
The NV T850 transaxle is available with the 2.4L
Gas and 2.5L Turbo Diesel engine options. Unique
gearing tailored to the performance characteristics of
each engine provides optimum driveability, gradabil-
ity, and acceleration. The gear ratios are as follows:
GEARRATIO
(2.4L Gas)RATIO
(2.5L TD)
1st 3.65 3.46
2nd 2.07 2.05
3rd 1.39 1.37
4th 1.03 0.97
5th 0.83 0.76
Reverse 3.47 3.47
Final Drive
Ratio3.77 3.53
Overall Top
Gear3.12 2.66
TRANSAXLE IDENTIFICATION
NOTE: Since transaxles use unique gear ratios for
each of the two engine applications, it is imperative
that the transaxle is properly identified, and the cor-
rect transaxle assembly number is used when
ordering service parts.The transaxle model, assembly part number, build
date, and final drive ratio (FDR) can be found on a
metal tag fastened to the transaxle case on the bell-
housing (Fig. 2). A barcode label is also glued to the
transaxle bellhousing, and it too includes the trans-
axle part number.
Fig. 2 T850 Transaxle Identification
1 - TRANSAXLE BELLHOUSING
2 - BARCODE LABEL
3 - I.D. TAG
RGT850 MANUAL TRANSAXLE21a-3
T850 MANUAL TRANSAXLE (Continued)
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