1998 DODGE RAM 1500 heating

(6) Check converter seating with a scale and
straightedge (Fig. 235). Surface of converter lugs
should be 19mm (0.75 in.) to the rear of the straight-
edge when converter is fully seated.
(7) If necessary, temporarily secure converter with
C-clamp attached to the converter housing.
(8) Install the transmission in the vehicle.
(9) Fill the transmission with the recommended
fluid.
TORQUE CONVERTER
DRAINBACK VALVE
DESCRIPTION
The drainback valve is located in the transmission
cooler outlet (pressure) line.
OPERATION
The valve prevents fluid from draining from the
converter into the cooler and lines when the vehicle
is shut down for lengthy periods. Production valves
have a hose nipple at one end, while the opposite end
is threaded for a flare fitting. All valves have an
arrow (or similar mark) to indicate direction of flow
through the valve.
STANDARD PROCEDURE - TORQUE
CONVERTER DRAINBACK VALVE
The converter drainback check valve is located in
the cooler outlet (pressure) line near the radiator
tank. The valve prevents fluid drainback when the
vehicle is parked for lengthy periods. The valve check
ball is spring loaded and has an opening pressure of
approximately 2 psi.
The valve is serviced as an assembly; it is not
repairable. Do not clean the valve if restricted, or
contaminated by sludge, or debris. If the valve fails,
or if a transmission malfunction occurs that gener-
ates significant amounts of sludge and/or clutch par-
ticles and metal shavings, the valve must be
replaced.
If the valve is restricted, installed backwards, or in
the wrong line, it will cause an overheating condition
and possible transmission failure.
CAUTION: The drainback valve is a one-way flow
device. It must be properly oriented in terms of flow
direction for the cooler to function properly. The
valve must be installed in the pressure line. Other-
wise flow will be blocked and would cause an over-
heating condition and eventual transmission failure.
TOW/HAUL OVERDRIVE
SWITCH
DESCRIPTION
The tow/haul overdrive OFF (control) switch is
located in the shift lever arm (Fig. 236). The switch
is a momentary contact device that signals the PCM
to toggle current status of the overdrive function.
Fig. 235 Typical Method Of Checking Converter
Seating
1 - SCALE
2 - STRAIGHTEDGE
Fig. 236 Tow/Haul Overdrive Off Switch
DRAUTOMATIC TRANSMISSION - 48RE 21 - 261
TORQUE CONVERTER (Continued)

FLUID AND FILTER
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - EFFECTS OF
INCORRECT FLUID LEVEL
A low fluid level allows the pump to take in air
along with the fluid. Air in the fluid will cause fluid
pressures to be low and develop slower than normal.
If the transmission is overfilled, the gears churn the
fluid into foam. This aerates the fluid and causing
the same conditions occurring with a low level. In
either case, air bubbles cause fluid overheating, oxi-
dation and varnish buildup which interferes with
valve and clutch operation. Foaming also causes fluid
expansion which can result in fluid overflow from the
transmission vent or fill tube. Fluid overflow can eas-
ily be mistaken for a leak if inspection is not careful.
DIAGNOSIS AND TESTING - CAUSES OF
BURNT FLUID
Burnt, discolored fluid is a result of overheating
which has three primary causes.
(1) Internal clutch slippage, usually caused by low
line pressure, inadequate clutch apply pressure, or
clutch seal failure.
(2) A result of restricted fluid flow through the
main and/or auxiliary cooler. This condition is usu-
ally the result of a faulty or improperly installed
drainback valve, a damaged main cooler, or severe
restrictions in the coolers and lines caused by debris
or kinked lines.
(3) Heavy duty operation with a vehicle not prop-
erly equipped for this type of operation. Trailer tow-
ing or similar high load operation will overheat the
transmission fluid if the vehicle is improperly
equipped. Such vehicles should have an auxiliary
transmission fluid cooler, a heavy duty cooling sys-
tem, and the engine/axle ratio combination needed to
handle heavy loads.
DIAGNOSIS AND TESTING - FLUID
CONTAMINATION
Transmission fluid contamination is generally a
result of:
²adding incorrect fluid
²failure to clean dipstick and fill tube when
checking level
²engine coolant entering the fluid
²internal failure that generates debris
²overheat that generates sludge (fluid break-
down)
²failure to replace contaminated converter after
repairThe use of non-recommended fluids can result in
transmission failure. The usual results are erratic
shifts, slippage, abnormal wear and eventual failure
due to fluid breakdown and sludge formation. Avoid
this condition by using recommended fluids only.
The dipstick cap and fill tube should be wiped
clean before checking fluid level. Dirt, grease and
other foreign material on the cap and tube could fall
into the tube if not removed beforehand. Take the
time to wipe the cap and tube clean before withdraw-
ing the dipstick.
Engine coolant in the transmission fluid is gener-
ally caused by a cooler malfunction. The only remedy
is to replace the radiator as the cooler in the radiator
is not a serviceable part. If coolant has circulated
through the transmission, an overhaul is necessary.
The torque converter should also be replaced when-
ever a failure generates sludge and debris. This is
necessary because normal converter flushing proce-
dures will not remove all contaminants.
STANDARD PROCEDURE
STANDARD PROCEDURE - FLUID LEVEL
CHECK
Low fluid level can cause a variety of conditions
because it allows the pump to take in air along with
the fluid. As in any hydraulic system, air bubbles
make the fluid spongy, therefore, pressures will be
low and build up slowly.
Improper filling can also raise the fluid level too
high. When the transmssion has too much fluid, the
geartrain churns up foam and cause the same condi-
tions which occur with a low fluid level.
In either case, air bubbles can cause overheating
and/or fluid oxidation, and varnishing. This can
interfere with normal valve, clutch, and accumulator
operation. Foaming can also result in fluid escaping
from the transmission vent where it may be mis-
taken for a leak.
After the fluid has been checked, seat the dipstick
fully to seal out water and dirt.
The transmission has a dipstick to check oil level.
It is located on the right side of the engine. Be sure
to wipe all dirt from dipstick handle before removing.
The torque converter fills in both the P (PARK)
and N (NEUTRAL) positions. Place the selector lever
in P (PARK) to be sure that the fluid level check is
accurate.The engine should be running at idle
speed for at least one minute, with the vehicle
on level ground.At normal operating temperature
(approximately 82 C. or 180 F.), the fluid level is cor-
rect if it is in the HOT region (cross-hatched area) on
the oil level indicator. The fluid level will be approx-
21 - 366 AUTOMATIC TRANSMISSION - 45RFE/545RFEDR

WHEELS
DESCRIPTION
Original equipment wheels are designed for the
specified Maximum Vehicle Capacity.
All models use steel or aluminum drop center
wheels.
Aluminum wheels require special balance weights
and alignment equipment.
(1) On vehicles equipped with dual rear wheels,
The rim is an eight stud hole pattern wheel. The
wheels have a flat mounting surface (Fig. 18). The
slots in the wheel must be aligned to provide access
to the valve stem (Fig. 19).
OPERATION
The wheel (Fig. 20) has raised sections between
the rim flanges and the rim well. Initial inflation of
the tire forces the bead over these raised sections. In
case of tire failure, the raised sections hold the tire
in position on the wheel until the vehicle can be
brought to a safe stop.
DIAGNOSIS AND TESTING
WHEEL INSPECTION
Inspect wheels for:
²Excessive run out
²Dents or cracks
²Damaged wheel lug nut holes
²Air Leaks from any area or surface of the rim
NOTE: Do not attempt to repair a wheel by hammer-
ing, heating or welding.
If a wheel is damaged an original equipment
replacement wheel should be used. When obtaining
replacement wheels, they should be equivalent in
load carrying capacity. The diameter, width, offset,
pilot hole and bolt circle of the wheel should be the
same as the original wheel.
WARNING: FAILURE TO USE EQUIVALENT
REPLACEMENT WHEELS MAY ADVERSELY
AFFECT THE SAFETY AND HANDLING OF THE
VEHICLE. USED WHEELS ARE NOT RECOM-
MENDED. THE SERVICE HISTORY OF THE WHEEL
MAY HAVE INCLUDED SEVERE TREATMENT OR
VERY HIGH MILEAGE. THE RIM COULD FAIL WITH-
OUT WARNING.
Fig. 18 FLAT FACE WHEEL
1 - FLAT FACE
2 - VALVE STEM
Fig. 19 DUAL REAR WHEELS
1 - WINDOW OPENINGS (5)
2 - INBOARD VALVE STEM
3 - OUTBOARD VALVE STEM
Fig. 20 Safety Rim
1 - FLANGE
2 - RIDGE
3 - WELL
DRTIRES/WHEELS 22 - 11

STANDARD PROCEDURE
STANDARD PROCEDURE - WHEEL
REPLACEMENT
The wheel studs and nuts are designed for specific
applications. They must be replaced with equivalent
parts. Do not use replacement parts of lesser quality
or a substitute design. All aluminum and some steel
wheels have wheel stud nuts which feature an
enlarged nose. This enlarged nose is necessary to
ensure proper retention of the aluminum wheels.
NOTE: Do not use chrome plated lug nuts with
chrome plated wheels.
Before installing the wheel, be sure to remove any
build up of corrosion on the wheel mounting surfaces.
Ensure wheels are installed with good metal-to-metal
contact. Improper installation could cause loosening
of wheel nuts (Fig. 21). This could affect the safety
and handling of your vehicle.
To install the wheel, first position it properly on
the mounting surface (Fig. 21). All wheel nuts should
then be tightened just snug. Gradually tighten them
in sequence to the proper torque specification, (Fig.
22) (Fig. 23).Never use oil or grease on studs or
nuts.
Wheels must be replaced if they have:
²Excessive runout
²Bent or dented
²Leak air through welds
²Have damaged bolt holes
Wheel repairs employing hammering, heating, or
welding are not allowed.Original equipment wheels are available through
your dealer. Replacement wheels from any other
source should be equivalent in:
²Load carrying capacity
²Diameter
²Width
²Offset
²Mounting configuration
Failure to use equivalent replacement wheels may
affect the safety and handling of your vehicle.
Replacement withusedwheels is not recommended.
Their service history may have included severe treat-
ment.
STANDARD PROCEDURE - DUAL REAR WHEEL
INSTALLATION
Dual rear wheels use a special heavy duty lug nut
wrench. It is recommended to remove and install
dual rear wheels only when the proper wrench is
available. The wrench is also use to remove wheel
Fig. 21 WHEEL INSTALLATION 8-LUG SHOWN
1 - CENTER CAP
2 - LUG NUT
3 - TIRE/WHEEL ASSEMBLY
4 - WHEEL STUDS
Fig. 22 8-LUG TIGHTENING PATTERN
Fig. 23 TYPICAL 6 - LUG NUT TIGHTENING
PATTERN
22 - 12 TIRES/WHEELSDR
WHEELS (Continued)

CODE FAMILY NAME COMMON TRADE NAME TYPICAL APPLICATION
RRIM REINFORCED REACTION
INJECTED MOLDEDPUR, RRIM FASCIAS, BODY PANELS,
BODY TRIMS
TPE THERMO POLYETHYLENE TPE, HYTREL, BEXLOY-V FASCIAS, BUMPERS,
CLADDINGS
TPO THERMOPOLYOLEFIN POLYTROPE, RENFLEX,
SANTOPRENE, VISAFLEX,
ETA, APEX, TPO, SHIELDS,
CLADDINGSBUMPERS, END CAPS,
TELCAR, RUBBER, STRIPS,
SIGHT, INTERIOR B POST
TPP THERMO-POLYPROPYLENE TPP BUMPERS
TPU THERMOPOLYURETHANE,
POLYESTERTPU, HYTREL, TEXIN,
ESTANEBUMPERS, BODY SIDE,
MOLDINGS, FENDERS,
FASCIAS
PANEL SECTIONING
If it is required to section a large panel for a plas-
tic repair, it will be necessary to reinforce the panel
(Fig. 1). To bond two plastic panels together, a rein-
forcement must overlap both panels. The panels
must be ªV'dº at a 20 degree angle. The area to be
reinforced should be washed, then sanded. Be sure to
wipe off any excess soap and water when finished.
Lightly sand or abrade the plastic with an abrasive
pad or sandpaper. Blow off any dust with compressed
air or wipe with a clean dry rag.
When bonding plastic panels, Follow repair mate-
rial manufacturers recommendations. Be sure that
enough adhesive has been applied to allow squeeze
out and to fill the full bond line. Once the pieces
have been brought together, do not move them until
the adhesive is cured. The assembly can be held
together with clamps, rivets, etc. A faster cure can be
obtained by heating with a heat lamp or heat gun.After the parts have been bonded and have had time
to cure, rough sand the seam and apply the final
adhesive filler to the area being repaired. Smooth the
filler with a spreader, wooden tongue depressor, or
squeegee. For fine texturing, a small amount of
water can be applied to the filler surface while
smoothing. The cured filler can be sanded as neces-
sary and, as a final step, cleanup can be done with
soapy water. Wipe the surface clean with a dry cloth
allowing time for the panel to dry before moving on
with the repair.
PANEL REINFORCEMENT
Structural repair procedures for rigid panels with
large cracks and holes will require a reinforcement
backing. Reinforcements can be made with several
applications of glass cloth saturated with structural
adhesive. Semi-rigid or flexible repair materials
should be used for semi-rigid or flexible backing rein-
forcement (Fig. 2) and (Fig. 3). Open meshed fiber-
glass dry wall tape can be used to form a
reinforcement. The dry wall tape allows the resin to
penetrate through and make a good bond between
the panel and the adhesive. Structurally, the more
dry wall tape used, the stronger the repair.
Another kind of repair that can be done to repair
large cracks and holes is to use a scrap piece of sim-
ilar plastic and bond with structural adhesive. The
reinforcement should cover the entire break and
should have a generous amount of overlap on either
side of the cracked or broken area.
When repairing plastic, the damaged area is first
ªV'dº out, or beveled. Large bonding areas are desir-
able when repairing plastic because small repairs are
less likely to hold permanently. Beveling the area
around a crack at a 20 degree angle will increase the
bonding surface for a repair (Fig. 4). It is recom-
mended that sharp edges be avoided because the
joint may show through after the panel is refinished.
Fig. 1 PANEL SECTIONING
1 - EXISTING PANEL
2 - NEW PANEL
3 - PANEL ADHESIVE
4 - BONDING STRIP
23 - 6 BODYDR
BODY (Continued)

EXTERIOR
TABLE OF CONTENTS
page page
BODY SIDE MOLDINGS
REMOVAL.............................36
INSTALLATION.........................36
BODY ISOLATORS
REMOVAL.............................36
INSTALLATION.........................37
CARGO BOX
REMOVAL.............................37
INSTALLATION.........................37
CARGO BOX - TIE DOWN
REMOVAL.............................38
INSTALLATION.........................38
COWL GRILLE
REMOVAL.............................38
INSTALLATION.........................38
EXTERIOR NAME PLATES
REMOVAL.............................38
INSTALLATION.........................38
FRONT FENDER
REMOVAL.............................39
INSTALLATION.........................39
FUEL FILL DOOR
REMOVAL.............................39
INSTALLATION.........................39GRILLE
REMOVAL.............................40
INSTALLATION.........................40
GRILLE FRAME
REMOVAL.............................40
INSTALLATION.........................40
FRONT WHEELHOUSE SPLASH SHIELD
REMOVAL.............................41
INSTALLATION.........................41
REAR WHEELHOUSE SPLASH SHIELD
REMOVAL.............................41
INSTALLATION.........................41
SIDE VIEW MIRROR
REMOVAL.............................41
INSTALLATION.........................42
UPPER RADIATOR CROSSMEMBER
REMOVAL.............................42
INSTALLATION.........................42
SIDE VIEW MIRROR GLASS
REMOVAL.............................42
INSTALLATION.........................43
REAR FENDER
REMOVAL.............................44
INSTALLATION.........................44
BODY SIDE MOLDINGS
REMOVAL
NOTE: Body side moldings are attached to the body
panels with adhesive tape.
(1) Apply a length of masking tape on the body
panel, parallel to the top edge of the molding and to
one end to use as a guide for installation, if neces-
sary.
(2) If temperature is below 21ÉC (70ÉF) warm
molding with a heat lamp or gun. Do not exceed 52ÉC
(120ÉF) when heating molding.
(3) Using a trim stick C-4755 or equivalent,
remove and discard the molding from the outside of
the body panel.
INSTALLATION
(1) Thoroughly clean all residue from the body side
molding attachment area of the body panel.(2) Wipe area with a clean lint free cloth moist-
ened with a 50% solution of water and alcohol and
wipe dry immediately with a dry lint free cloth.
(3) Apply new body side molding using the guide
tape on the body panel and apply consistent and uni-
form pressure of approximately 40 p.s.i. over the
entire surface of the molding.
BODY ISOLATORS
REMOVAL
(1) Loosen all cab to frame mounting bolts (six
standard cab, eight quad cab). (Fig. 1)
(2) Remove the mounting bolts and rebound cush-
ions
(3) Using a floor jack and block of wood under the
cab sill, lift the body to gain access to the isolators.
(4) Remove the isolators.
(5) Install new isolators and repeat steps one
through 4, for the opposite side.
23 - 36 EXTERIORDR

CARGO BOX - TIE DOWN
REMOVAL
(1) Remove the bolts and remove the tie down
cleat. (Fig. 4)
INSTALLATION
(1) Install the tie down cleat and install the bolts.
(2) Tighten the bolts to 34 N´m (25 ft. lbs.).
COWL GRILLE
REMOVAL
(1) Remove the wiper arms. (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/WIPER ARMS -
REMOVAL)
(2) Disconnect the washer hose.
(3) Remove the hood seal.
(4) Remove the six push pin fasteners from the
front of the grille. (Fig. 5)
(5) Remove the two rear corner screws and remove
the grilles.
INSTALLATION
(1) Install the grill and install the two rear corner
screws.
(2) Install the six push pin fasteners along the
front of the grille.
(3) Install the hood seal.
(4) Connect the washer hose.(5) Install the wiper arms. (Refer to 8 - ELECTRI-
CAL/WIPERS/WASHERS/WIPER ARMS - INSTAL-
LATION)
EXTERIOR NAME PLATES
REMOVAL
NOTE: Exterior name plates are attached to body
panels with adhesive tape.
(1) Apply a length of masking tape on the body,
parallel to the top edge and one end of the name
plate to use as a guide for installation, if necessary.
(2) If temperature is below 21ÉC (70ÉF) warm
emblem with a heat lamp or gun. Do not exceed 52ÉC
(120ÉF) when heating name plate.
(3) Using a trim stick C-4755 or equivalent,
remove and discard the name plate.
INSTALLATION
(1) Thoroughly clean all residue from the name
plate attachment area of the body panel.
(2) Wipe area with a clean lint free cloth moist-
ened with a 50% solution of water and alcohol and
wipe dry immediately with a dry lint free cloth.
(3) Remove protective cover from adhesive tape on
back of name plate.
(4)
Position name plate properly on the body panel.
(5) Apply consistent and uniform pressure over the
entire surface of the name plate, with palm of hand.
(6) If temperature is below 21ÉC (70ÉF) warm
emblem with a heat lamp or gun to assure adhesion.
Do not exceed 52ÉC (120ÉF) when heating name
plate.
Fig. 4 TIE DOWN CLEAT
1 - BOLTS (2)
2 - CLEAT
Fig. 5 COWL GRILLE
1 - PUSH PIN FASTENERS (6)
2 - COWL GRILLE
3 - SCREWS (2)
23 - 38 EXTERIORDR

HEATING & AIR CONDITIONING
TABLE OF CONTENTS
page page
HEATING & AIR CONDITIONING
DESCRIPTION
DESCRIPTION - ENGINE COOLING
SYSTEM REQUIREMENTS...............1
DESCRIPTION - HEATER AND AIR
CONDITIONER........................1
OPERATION - HEATER AND AIR
CONDITIONER........................1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - A/C
PERFORMANCE.......................3DIAGNOSIS AND TESTING - HEATER
PERFORMANCE TEST..................6
SPECIFICATIONS - A/C SYSTEM............7
CONTROLS.............................9
DISTRIBUTION..........................26
PLUMBING.............................41
HEATING & AIR
CONDITIONING
DESCRIPTION
DESCRIPTION - ENGINE COOLING SYSTEM
REQUIREMENTS
To maintain the performance level of the heating,
ventilation and air conditioning (HVAC) system, the
engine cooling system must be properly maintained.
The use of a bug screen is not recommended. Any
obstructions in front of the radiator or A/C condenser
will reduce the performance of the A/C and engine
cooling systems.
The engine cooling system includes the radiator,
thermostat, radiator hoses and the engine coolant
pump. Refer to Cooling for more information before
opening or attempting any service to the engine cool-
ing system.
DESCRIPTION - HEATER AND AIR
CONDITIONER
A manually controlled single zone type heating-air
conditioning system or a manually controlled dual
zone type heating-air conditioning system is available
on this model.
All vehicles are equipped with a common heater,
ventilation and air conditioning (HVAC) housing (Fig.
1). The system combines air conditioning, heating,
and ventilating capabilities in a single unit housing
mounted within the passenger compartment under
the instrument panel. The HVAC housing includes:
²Blower motor
²Blower motor resistor block²Heater core
²Evaporator coil
²Blend door and actuator
²Defrost door and actuator
²Mode door and actuator
²Recirculation door and actuator
Based upon the system and mode selected, condi-
tioned air can exit the HVAC housing through one or
a combination of the three main housing outlets:
defrost, panel or floor. The defrost outlet is located on
the top of the housing, the panel outlet is located on
the face of the housing and the floor outlet is located
on the bottom of the housing. Once the conditioned
air exits the unit housing, it is further directed
through molded plastic ducts to the various outlets in
the vehicle interior. These outlets and their locations
are as follows:
²Defroster Outlet- A single large defroster out-
let is located in the center of the instrument panel
top cover, near the base of the windshield.
²Side Window Demister Outlets- There are
two side window demister outlets, one is located at
each outboard end of the instrument panel top cover,
near the belt line at the A-pillars.
²Panel Outlets- There are four panel outlets in
the instrument panel, one located near each outboard
end of the instrument panel facing the rear of the
vehicle and two located near the top of the instru-
ment panel center bezel.
²Front Floor Outlets- There are two front floor
outlets, one located above each side of the floor panel
center tunnel near the dash panel.
OPERATION - HEATER AND AIR CONDITIONER
The heating and air conditioning systems pulls
outside (ambient) air through the cowl opening at the
base of the windshield, then into the plenum cham-
DRHEATING & AIR CONDITIONING 24 - 1