1998 DODGE RAM 1500 body control module

TRANSMISSION
TEMPERATURE SENSOR
DESCRIPTION
Transmission fluid temperature readings are sup-
plied to the transmission control module by the ther-
mistor (Fig. 248). The temperature readings are used
to control engagement of the fourth gear overdrive
clutch, the converter clutch, and governor pressure.
Normal resistance value for the thermistor at room
temperature is approximately 2000 ohms.
The thermistor is part of the governor pressure
sensor assembly and is immersed in transmission
fluid at all times.
OPERATION
The PCM prevents engagement of the converter
clutch and overdrive clutch, when fluid temperature
is below approximately 10ÉC (50ÉF).
If fluid temperature exceeds 126ÉC (260ÉF), the
PCM causes a 4-3 downshift and engage the con-
verter clutch. Engagement is according to the third
gear converter clutch engagement schedule.
The Tow/Haul lamp in the instrument panel illumi-
nates when the shift back to third occurs. The trans-
mission will not allow fourth gear operation until
fluid temperature decreases to approximately 110ÉC
(230ÉF).
VALVE BODY
DESCRIPTION
The valve body consists of a cast aluminum 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, bands,
and frictional clutches. The valve body contains the
following components (Fig. 249), (Fig. 250), (Fig.
251), and (Fig. 252):
²Regulator valve
²Regulator valve throttle pressure plug
²Line pressure sleeve
²Kickdown valve
²Kickdown limit valve
²1-2 shift valve
²1-2 control valve
²2-3 shift valve
²2-3 governor plug
²3-4 shift valve
²3-4 timing valve
²3-4 quick fill valve
²3-4 accumulator
²Throttle valve
²Throttle pressure plug
²Switch valve
²Manual valve
²Converter clutch lock-up valve
²Converter clutch lock-up timing Valve
²Shuttle valve
²Shuttle valve throttle plug
²Boost Valve
²9 check balls
By adjusting the spring pressure acting on the reg-
ulator valve, transmission line pressure can be
adjusted.
Fig. 248 Governor Pressure Sensor
1 - GOVERNOR BODY
2 - GOVERNOR PRESSURE SENSOR/TRANSMISSION FLUID
TEMPERATURE THERMISTOR
DRAUTOMATIC TRANSMISSION - 48RE 21 - 267

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)

(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)

INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-
VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
(1) Seat the bottom of the receiver into position.
(2) Pivot the receiver forward and seat the retain-
ing clips fully.
CUP HOLDER
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-
VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
(1) Remove the center bezel.(Refer to 23 - BODY/
INSTRUMENT PANEL/INSTRUMENT PANEL
CENTER BEZEL - REMOVAL)
(2) Remove the airbag control module trim cover.
(Fig. 4)
(3) Open the cupholder and fold down the inner
panel.
(4) Remove the two inner screws. (Fig. 5)
(5) Remove the remaining two top and bottom
screws and remove the cup holder. (Fig. 6)
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERINGCOLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-
VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
Fig. 4 INSTRUMENT PANEL COVERS
1 - TOP COVER
2 - INSTRUMENT PANEL
3 - AIR BAG MODULE COVER
4 - END CAP
Fig. 5 CUPHOLDER - INNER FASTENERS
1 - CUPHOLDER
2 - INNER SCREWS (2)
DRINSTRUMENT PANEL 23 - 51
ASH RECEIVER (Continued)

(1) Install the cupholder and install the two upper
screws from the left to the right.
(2) Install the lower two screws from the left to
the right.
(3) Fold down the inner cover and install the two
inner screws.
(4) Install the center bezel. (Refer to 23 - BODY/
INSTRUMENT PANEL/INSTRUMENT PANEL
CENTER BEZEL - INSTALLATION)
(5) Install the airbag control module trim cover.
GLOVE BOX
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-
VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
(1) Partially open the glove box.(2) From the inside of the box press down on the
rearward edge of the bin and lower the glove box
fully past the stops.
(3) Lift the box assembly off of the hinges and
remove.
INSTALLATION
(1) Engage the glove box hinges and partially
close.
(2) From the inside of the box press down on the
rearward edge of the bin and raise the glove box fully
past the stops.
(3) Check for proper glove box operation.
GLOVE BOX LATCH
REMOVAL
(1) Remove the glove box. (Refer to 23 - BODY/IN-
STRUMENT PANEL/GLOVE BOX - REMOVAL)
(2) Remove the 11 screws and separate the box
and inner panel from the outer door.
(3) Remove the two latch screws and remove the
latch.
INSTALLATION
(1) Install the latch and install the two screws.
(2) Install the door inner cover and box and install
the 11 screws.
(3) Install the glove box. (Refer to 23 - BODY/IN-
STRUMENT PANEL/GLOVE BOX - INSTALLA-
TION)
INSTRUMENT PANEL
ASSEMBLY
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-
VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
Fig. 6 CUPHOLDER - OUTER FASTENERS
1 - SCREWS (4)
2 - CUPHOLDER
23 - 52 INSTRUMENT PANELDR
CUP HOLDER (Continued)

(1) Remove the left a-pillar trim. (Refer to 23 -
BODY/INTERIOR/A-PILLAR TRIM/GRAB HANDLE
- REMOVAL)
(2) Remove the top cover. (Refer to 23 - BODY/IN-
STRUMENT PANEL/INSTRUMENT PANEL TOP
COVER - REMOVAL)
(3) Disconnect the headliner harness electrical con-
nector at the a-pillar.
(4) Using a trim stick C-4755 or equivalent, from
the notch on the bottom, remove the left side cover.
(Fig. 20)
(5) Remove the steering column. (Refer to 19 -
STEERING/COLUMN - REMOVAL)
(6) Remove the two bolts at the column support
bracket. (Fig. 7)
(7) Remove the left cowl trim panel. (Refer to 23 -
BODY/INTERIOR/COWL TRIM - REMOVAL)
(8) Remove the instrument panel drivers side
bezel. (Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL DRIVERS SIDE BEZEL -
REMOVAL)
(9) Remove the left side mounting bolts. (Fig. 8)
(10) Disconnect the wire harness electrical connec-
tors above the brake pedal. (Fig. 9)
(11) Loosen the screws and remove the hood
release handle from the bracket.
(12) Disconnect the park brake release handle
actuator rod.(13) Remove the air bag control module trim cover,
if equipped. (Fig. 20)
Fig. 7 COLUMN SUPPORT
1 - INSTRUMENT PANEL CLUSTER BEZEL
2 - STEERING COLUMN SUPPORT BRACKET
3 - BOLTS
Fig. 8 LEFT SIDE MOUNTING
1 - A-PILLAR
2 - INSTRUMENT PANEL
3 - MOUNTING BOLTS (3)
Fig. 9 WIRE HARNESS CONNECTORS
1 - BULKHEAD CONNECTORS
2 - INSTRUMENT PANEL HARNESS CONNECTORS
DRINSTRUMENT PANEL 23 - 53
INSTRUMENT PANEL ASSEMBLY (Continued)

(14) Remove the floor console, if equipped. (Refer
to 23 - BODY/INTERIOR/FLOOR CONSOLE -
REMOVAL)
(15) Remove the center bracket bolts. (Fig. 10)
(16) Disconnect the air bag control module electri-
cal connector.
(17) Remove the right cowl trim cover. (Refer to 23
- BODY/INTERIOR/COWL TRIM - REMOVAL)
(18) Disconnect the two electrical connectors. (Fig.
11 )(19) Disconnect the radio antenna. (Fig. 12)
(20) Remove the one HVAC screw. (Fig. 13)
(21) Using a trim stick C-4755 or equivalent, from
the notch on the bottom, remove the right end cap.
(Fig. 14)
(22) Remove the right a-pillar trim. (Refer to 23 -
BODY/INTERIOR/A-PILLAR TRIM/GRAB HANDLE
- REMOVAL)
Fig. 10 CENTER MOUNTING BOLTS
1 - INSTRUMENT PANEL
2 - BOLTS
Fig. 11 RIGHT WIRE HARNESS CONNECTIONS
1 - COWL SIDE PANEL
2 - ELECTRICAL CONNECTORS
Fig. 12 ANTENNA CONNECTION
1 - ANTENNA CABLE
2 - RADIO CABLE
Fig. 13 HVAC/INSTRUMENT PANEL MOUNTING
1-HVAC
2 - MOUNTING SCREW
3 - LOWER SURROUND SCREWS
4 - GLOVE BOX OPENING
23 - 54 INSTRUMENT PANELDR
INSTRUMENT PANEL ASSEMBLY (Continued)

(8) Install the left a-pillar trim. (Refer to 23 -
BODY/INTERIOR/A-PILLAR TRIM - INSTALLA-
TION)
(9) Position the left end cap and seat the attach-
ment clips fully.
(10) Install the right side mounting bolts on the
a-pillar and one right mounting bolt on the cowl side
panel and tighten to 12 N´m (9 ft. lbs.).
(11) Install the right a-pillar trim panel. (Refer to
23 - BODY/INTERIOR/A-PILLAR TRIM - INSTAL-
LATION)
(12) Position the right end cap and seat the
attachment clips fully.
(13) Install the one HVAC mounting screw.
(14) Connect the radio antenna.
(15) Connect the two electrical connectors at the
right cowl panel.
(16) Install the right cowl trim cover. (Refer to 23 -
BODY/INTERIOR/COWL TRIM - INSTALLATION)
(17) Connect the air bag control module electrical
connector.
(18) Install the center bracket bolts and tighten to
12 N´m (9 ft. lbs.).
(19) Install the floor console, if equipped. (Refer to
23 - BODY/INTERIOR/FLOOR CONSOLE - INSTAL-
LATION)
(20) Install the air bag control module cover, if
equipped.
(21) Connect the park brake release handle actua-
tor rod.
(22) Install the hood release handle and tighten
the screws.
(23) Install the two bolts at the column support
bracket and tighten to 14 N´m (10 ft. lbs.).
(24) Install the steering column. (Refer to 19 -
STEERING/COLUMN - INSTALLATION)
(25) Connect the wire harness electrical connectors
above the brake pedal.
(26) Install the two top instrument panel bolts and
tighten to 12 N´m (9 ft. lbs.).
(27) Install the four top instrument panel screws.
(28) Install the instrument panel top cover. (Refer
to 23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL TOP COVER - INSTALLATION)
INSTRUMENT PANEL
HEADLAMP SWITCH BEZEL
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
(1) Using a trim stick C-4755 or equivalent,
release the top clips on the steering column opening
cover and the lower drivers side bezel.
(2) Using a trim stick C-4755 or equivalent,
release the switch bezel. (Fig. 17)
(3) Disconnect the electrical connector and remove
the bezel.
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-
VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
(1) Connect the electrical connector.
Fig. 17 HEADLIGHT SWITCH BEZEL
1 - SWITCH BEZEL
2 - INSTRUMENT PANEL
3 - ELECTRICAL CONNECTOR
4 - HEADLIGHT SWITCH
23 - 56 INSTRUMENT PANELDR
INSTRUMENT PANEL ASSEMBLY (Continued)