1998 DODGE RAM 1500 Body

into the appropriate oil pump valve body bore (Fig.
102) (Fig. 103).
(4) Place the separator plate onto the oil pump
body (Fig. 101).
(5) Install the screws to hold the separator plate
onto the oil pump body (Fig. 101). Tighten the screws
to 4.5 N´m (40 in.lbs.).
(6) Position the oil pump cover onto the locating
dowels (Fig. 100).
(7) Seat the two oil pump halves together and
install all bolts finger tight.
(8) Torque all bolts down slowly starting in the
center and working outward. The correct torque is
4.5 N´m (40 in.lbs.).
(9) Verify that the oil pump gears rotate freely and
smoothly.
(10) Position the reaction shaft support into the oil
pump (Fig. 100).
(11) Install and torque the bolts to hold the reac-
tion shaft support to the oil pump (Fig. 100). The cor-
rect torque is 12 N´m (105 in.lbs.).
OIL PUMP FRONT SEAL
REMOVAL
(1) Remove transmission from the vehicle.
(2) Remove the torque converter from the trans-
mission.
(3) Using a screw mounted in a slide hammer,
remove the oil pump front seal.
INSTALLATION
(1) Clean seal bore of the oil pump of any residue
or particles from the original seal.
(2) Install new oil seal in the oil pump housing
using Seal Installer C-3860-A (Fig. 104).
OUTPUT SPEED SENSOR
DESCRIPTION
The Input and Output Speed Sensors are two-wire
magnetic pickup devices that generate AC signals as
rotation occurs. They are mounted in the left side of
the transmission case and are considered primary
inputs 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, an AC
voltage is generated and sent to the TCM. The TCM
interprets this information as input shaft rpm.
The Output Speed Sensor generates an AC signal
in a similar fashion, though its coil is excited by rota-
tion of the rear planetary carrier lugs. 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
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) Raise vehicle.
(2) Place a suitable fluid catch pan under the
transmission.
(3) Remove the wiring connector from the output
speed sensor (Fig. 105).
(4) Remove the bolt holding the output speed sen-
sor to the transmission case.
(5) Remove the output speed sensor from the
transmission case.
Fig. 104 Install Oil Pump Front Seal
1 - TOOL C-3860-A
DRAUTOMATIC TRANSMISSION - 45RFE/545RFE 21 - 391
OIL PUMP (Continued)

PRESSURE ON A CONFINED FLUID
Pressure is exerted on a confined fluid (Fig. 111) by
applying a force to some given area in contact with
the fluid. A good example of this is a cylinder filled
with fluid and equipped with a piston that is closely
fitted to the cylinder wall. If a force is applied to the
piston, pressure will be developed in the fluid. Of
course, no pressure will be created if the fluid is not
confined. It will simply ªleakº past the piston. There
must be a resistance to flow in order to create pres-
sure. Piston sealing is extremely important in
hydraulic operation. Several kinds of seals are used
to accomplish this within a transmission. These
include but are not limited to O-rings, D-rings, lip
seals, sealing rings, or extremely close tolerances
between the piston and the cylinder wall. The force
exerted is downward (gravity), however, the principle
remains the same no matter which direction is taken.
The pressure created in the fluid is equal to the force
applied, divided by the piston area. If the force is 100
lbs., and the piston area is 10 sq. in., then the pres-
sure created equals 10 PSI. Another interpretation of
Pascal's Law is that regardless of container shape or
size, the pressure will be maintained throughout, as
long as the fluid is confined. In other words, the
pressure in the fluid is the same everywhere within
the container.
FORCE MULTIPLICATION
Using the 10 PSI example used in the illustration
(Fig. 112), a force of 1000 lbs. can be moved with a
force of only 100 lbs. The secret of force multiplica-
tion in hydraulic systems is the total fluid contact
area employed. The illustration, (Fig. 112), shows an
area that is ten times larger than the original area.
The pressure created with the smaller 100 lb. input
is 10 PSI. The concept ªpressure is the same every-
whereº means that the pressure underneath the
larger piston is also 10 PSI. Pressure is equal to the
force applied divided by the contact area. Therefore,
by means of simple algebra, the output force may be
found. This concept is extremely important, as it is
also used in the design and operation of all shift
valves and limiting valves in the valve body, as well
as the pistons, of the transmission, which activate
the clutches and bands. It is nothing more than
using a difference of area to create a difference in
pressure to move an object.
Fig. 111 Pressure on a Confined Fluid
Fig. 112 Force Multiplication
21 - 394 AUTOMATIC TRANSMISSION - 45RFE/545RFEDR
PISTONS (Continued)

SHIFT MECHANISM
DESCRIPTION
The gear shift mechanism provides six shift posi-
tions which are:
²Park (P)
²Reverse (R)
²Neutral (N)
²Drive (D)
²Manual second (2)
²Manual low (1)
OPERATION
MANUAL LOW (1) range provides first gear only.
Overrun braking is also provided in this range.
MANUAL SECOND (2) range provides first and sec-
ond gear only.
DRIVE range provides FIRST, SECOND, THIRD,
OVERDRIVE FOURTH, and OVERDRIVE FIFTH (if
applicable) gear ranges. The shift into OVERDRIVE
FOURTH and FIFTH (if applicable) gear ranges
occurs only after the transmission has completed the
shift into D THIRD gear range. No further movement
of the shift mechanism is required to complete the
3-4 or 4-5 (if applicable) shifts.
The FOURTH and FIFTH (if applicable) gear
upshifts occur automatically when the overdrive
selector switch is in the ON position. No upshift to
FOURTH or FIFTH (if applicable) gears will occur if
any of the following are true:
²The transmission fluid temperature is below 10É
C (50É F) or above 121É C (250É F).
²The shift to THIRD is not yet complete.
²Vehicle speed is too low for the 3-4 or 4-5 (if
applicable) shifts to occur.
Upshifts into FOURTH or FIFTH (if applicable)
will be delayed when the transmission fluid temper-
ature is below 4.5É C (40É F) or above 115.5É C (240É
F).
SOLENOID SWITCH VALVE
DESCRIPTION
The Solenoid Switch Valve (SSV) is located in the
valve body and controls the direction of the transmis-
sion fluid when the L/R-TCC solenoid is energized.
OPERATION
The Solenoid Switch Valve controls line pressure
from the LR-TCC solenoid. In 1st gear, the SSV will
be in the downshifted position, thus directing fluid to
the L/R clutch circuit. In 2nd, 3rd, 4th, and 5th (if
applicable) gears, the solenoid switch valve will be in
the upshifted position and directs the fluid into the
torque converter clutch (TCC) circuit.When shifting into 1st gear, a special hydraulic
sequence is performed to ensure SSV movement into
the downshifted position. The L/R pressure switch is
monitored to confirm SSV movement. If the move-
ment is not confirmed (the L/R pressure switch does
not close), 2nd gear is substituted for 1st. A DTC will
be set after three unsuccessful attempts are made to
get into 1st gear in one given key start.
SOLENOIDS
DESCRIPTION
The typical electrical solenoid used in automotive
applications is a linear actuator. It is a device that
produces motion in a straight line. This straight line
motion can be either forward or backward in direc-
tion, and short or long distance.
A solenoid is an electromechanical device that uses
a magnetic force to perform work. It consists of a coil
of wire, wrapped around a magnetic core made from
steel or iron, and a spring loaded, movable plunger,
which performs the work, or straight line motion.
The solenoids used in transmission applications
are attached to valves which can be classified asnor-
mally openornormally closed. Thenormally
opensolenoid valve is defined as a valve which
allows hydraulic flow when no current or voltage is
applied to the solenoid. Thenormally closedsole-
noid valve is defined as a valve which does not allow
hydraulic flow when no current or voltage is applied
to the solenoid. These valves perform hydraulic con-
trol functions for the transmission and must there-
fore be durable and tolerant of dirt particles. For
these reasons, the valves have hardened steel pop-
pets and ball valves. The solenoids operate the valves
directly, which means that the solenoids must have
very high outputs to close the valves against the siz-
able flow areas and line pressures found in current
transmissions. Fast response time is also necessary
to ensure accurate control of the transmission.
The strength of the magnetic field is the primary
force that determines the speed of operation in a par-
ticular solenoid design. A stronger magnetic field will
cause the plunger to move at a greater speed than a
weaker one. There are basically two ways to increase
the force of the magnetic field:
1. Increase the amount of current applied to the
coil or
2. Increase the number of turns of wire in the coil.
The most common practice is to increase the num-
ber of turns by using thin wire that can completely
fill the available space within the solenoid housing.
The strength of the spring and the length of the
plunger also contribute to the response speed possi-
ble by a particular solenoid design.
21 - 398 AUTOMATIC TRANSMISSION - 45RFE/545RFEDR

(9) Fill the transmission with the recommended
fluid.
TRANSMISSION CONTROL
RELAY
DESCRIPTION
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.
OPERATION
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, the TCM energizes the
relay. Prior to this, the TCM verifies that the con-
tacts are open by checking 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 energized, the TCM mon-
itors the terminals to verify that the voltage is
greater than 3 volts.
TRANSMISSION RANGE
SENSOR
DESCRIPTION
The Transmission Range Sensor (TRS) is part of
the solenoid module, which is mounted to the top of
the valve body inside the transmission.
The Transmission Range Sensor (TRS) has five
switch contact pins that:
²Determine shift lever position
²Supply ground to the Starter Relay in Park and
Neutral only.
²
Supply +12 V to the backup lamps in Reverse only.
The TRS also has an integrated temperature sen-
sor (thermistor) that communicates transmission
temperature to the TCM and PCM.
OPERATION
The Transmission Range Sensor (TRS) communi-
cates shift lever position to the TCM as a combina-
tion 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 transmission gear posi-
tion and shift schedule.
There are many possible combinations of open and
closed switches (codes). Seven of these possible codes
are related to gear position and five are recognized
as ªbetween gearº codes. This results in many codes
which shouldnever 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.
GEAR C5 C4 C3 C2 C1
ParkCL OP OP CL CL
Temp 1CL OP OP CL OP
ReverseOP OP OP CL OP
Temp 2OP OP CL CL OP
Neutral 1OP OP CL CL CL
Neutral 2OP CL CL CL CL
Temp 3OP CL CL CL OP
DriveOP CL CL OP OP
Temp 4OP CL OP OP OP
Manual 2CL CL OP OP OP
Temp 5CL OP OP OP OP
Manual 1CL OP CL OP OP
Fig. 125 Checking Torque Converter Seating-Typical
1 - SCALE
2 - STRAIGHTEDGE
DRAUTOMATIC TRANSMISSION - 45RFE/545RFE 21 - 405
TORQUE CONVERTER (Continued)

TRANSMISSION SOLENOID/
TRS ASSEMBLY
DESCRIPTION
The transmission solenoid/TRS assembly is inter-
nal to the transmission and mounted on the valve
body assembly (Fig. 126). The assembly consists of
six solenoids that control hydraulic pressure to the
six friction elements (transmission clutches), and the
torque converter clutch. The pressure control sole-
noid is located on the side of the solenoid/TRS assem-
bly. The solenoid/TRS assembly also contains five
pressure switches that feed information to the TCM.
OPERATION
SOLENOIDS
Solenoids are used to control the L/R, 2C, 4C, OD,
and UD friction elements. The reverse clutch is con-
trolled by line pressure and the position of the man-
ual valve in the valve body. All the solenoids are
contained within the Solenoid and Pressure Switch
Assembly. The solenoid and pressure switch assembly
contains one additional solenoid, Multi-Select (MS),
which serves primarily to provide 2nd and 3rd gear
limp-in operation.
The solenoids receive electrical power from the
Transmission Control Relay through a single wire.
The TCM energizes or operates the solenoids individ-
ually by grounding the return wire of the solenoid as
necessary. When a solenoid is energized, the solenoid
valve shifts, and a fluid passage is opened or closed
(vented or applied), depending on its default operat-
ing state. The result is an apply or release of a fric-
tional element.
The MS and UD solenoids are normally applied to
allow transmission limp-in in the event of an electri-
cal 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. If 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.
Fig. 126 Transmission Solenoid/TRS Assembly
1 - PRESSURE CONTROL SOLENOID
2 - TRANSMISSION RANGE SELECTOR PLATE
3 - 23-WAY CONNECTOR
4 - SOLENOID PACK
5 - TRANSMISSION RANGE SENSOR
6 - VALVE BODY
21 - 406 AUTOMATIC TRANSMISSION - 45RFE/545RFEDR

PRESSURE SWITCHES
The TCM relies on five pressure switches to moni-
tor fluid pressure in the L/R, 2C, 4C, UD, and OD
hydraulic circuits. The primary purpose of these
switches is to help the TCM detect when clutch cir-
cuit hydraulic failures occur. The switches close at 23
psi and open at 11 psi, and simply indicate whether
or not pressure exists. The switches are continuously
monitored by the TCM for the correct states (open or
closed) in each gear as shown in the following charts
45RFE PRESSURE SWITCH STATES and 545RFE
PRESSURE SWITCH STATES :
45RFE PRESSURE SWITCH STATES
GEAR L/R 2C 4C UD OD
ROP OP OP OP OP
P/NCL OP OP OP OP
1STCL* OP OP CL OP
2NDOP CL OP CL OP
2ND
PRIMEOP OP CL CL OP
DOP OP OP CL CL
FOURTHOP OP CL OP CL
*L/R is closed if output speed is below 100 rpm in
Drive and Manual 2. L/R is open in Manual 1.
545RFE PRESSURE SWITCH STATES
GEAR L/R 2C 4C UD OD
ROP OP OP OP OP
P/NCL OP OP OP OP
1STCL* OP OP CL OP
2NDOP CL OP CL OP
2ND
PRIMEOP OP CL CL OP
DOP OP OP CL CL
4THOP OP CL OP CL
5THOP CL OP OP CL
*L/R is closed if output speed is below 100 rpm in
Drive and Manual 2. L/R is open in Manual 1.
A Diagnostic Trouble Code (DTC) will set if the
TCM senses any switch open or closed at the wrong
time in a given gear.
REMOVAL
(1) Remove the valve body from the transmission
(Fig. 127).
(2) Remove the screws holding the transmission
solenoid/TRS assembly onto the valve body (Fig. 128).
(3) Separate the transmission solenoid/TRS assem-
bly from the valve body.
Fig. 127 Valve Body Bolts
1 - VALVE BODY TO CASE BOLT (6)
Fig. 128 Transmission Solenoid/TRS Assembly
Screws
1 - SOLENOID PACK BOLTS (15)
DRAUTOMATIC TRANSMISSION - 45RFE/545RFE 21 - 407
TRANSMISSION SOLENOID/TRS ASSEMBLY (Continued)

INSTALLATION
(1) Place TRS selector plate in the PARK position.
(2) Position the transmission solenoid/TRS assem-
bly onto the valve body. Be sure that both alignment
dowels are fully seated in the valve body and that
the TRS switch contacts are properly positioned in
the selector plate
(3) Install the screws to hold the transmission
solenoid/TRS assembly onto the valve body.
(4) Tighten the solenoid assembly screws adjacent
to the arrows cast into the bottom of the valve body
first. Tighten the screws to 5.7 N´m (50 in.lbs.).
(5) Tighten the remainder of the solenoid assembly
screws to 5.7 N´m (50 in.lbs.).
(6) Install the valve body into the transmission.
TRANSMISSION
TEMPERATURE SENSOR
DESCRIPTION
The transmission temperature sensor is a ther-
mistor that is integral to the Transmission Range
Sensor (TRS).
OPERATION
The transmission temperature sensor is used by
the TCM to sense the temperature of the fluid in the
sump. Since fluid temperature can affect transmis-
sion shift quality and convertor lock up, the TCM
requires this information to determine which shift
schedule to operate in.
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
VALVE BODY
DESCRIPTION
The valve body consists of a cast aluminum valve
body, a separator plate, and a transfer plate. The
valve body contains valves and check balls that con-
trol fluid delivery to the torque converter clutch,
bands, and frictional clutches. The valve body con-
tains the following components (Fig. 129) and (Fig.
130):
²Solenoid switch valve
²Manual valve
²Low/reverse switch valve
²5 Accumulators
²7 check balls
OPERATION
NOTE: Refer to the Hydraulic Schematics for a
visual aid in determining valve location, operation
and design.
SOLENOID SWITCH VALVE
The Solenoid Switch Valve (SSV) controls the direc-
tion of the transmission fluid when the L/R-TCC sole-
noid is energized.
When shifting into 1st gear, a special hydraulic
sequence is performed to ensure SSV movement into
the downshifted position. The L/R pressure switch is
monitored to confirm SSV movement. If the move-
ment is not confirmed (the L/R pressure switch does
not close), 2nd gear is substituted for 1st. A DTC will
be set after three unsuccessful attempts are made to
get into 1st gear in one given key start.
MANUAL VALVE
The manual valve is a relay valve. The purpose of
the manual valve is to direct fluid to the correct cir-
cuit needed for a specific gear or driving range. The
manual valve, as the name implies, is manually oper-
ated by the driver with a lever located on the top of
the valve body. The valve is connected mechanically
by a cable to the gearshift mechanism. The valve is
held in each of its positions by a roller detent spring
(Fig. 131) that engages the ªroostercombº of the TRS
selector plate.
21 - 408 AUTOMATIC TRANSMISSION - 45RFE/545RFEDR
TRANSMISSION SOLENOID/TRS ASSEMBLY (Continued)

Fig. 129 Valve Body Components
1 - LOW/REVERSE ACCUMULATOR 6 - OVERDRIVE ACCUMULATOR
2 - LOW/REVERSE SWITCH VALVE 7 - UNDERDRIVE ACCUMULATOR
3 - UPPER VALVE BODY 8 - 4C ACCUMULATOR
4 - MANUAL VALVE 9 - 2C ACCUMULATOR
5 - SOLENOID SWITCH VALVE
Fig. 130 Check Ball Locations
Fig. 131 TRS Selector Plate and Detent Spring
1 - TRS SELECTOR PLATE
2 - DETENT SPRING
3 - CLUTCH PASSAGE SEALS
DRAUTOMATIC TRANSMISSION - 45RFE/545RFE 21 - 409
VALVE BODY (Continued)