1998 DODGE RAM 1500 Egr

MODE SENSOR
DESCRIPTION
The transfer case mode sensor (Fig. 94) is an elec-
tronic device whose output can be interpreted to indi-
cate the shift motor shaft's rotary position. The
sensor consists of a magnetic ring and four Hall
Effect Transistors to create a 4 channel digital device
(non-contacting) whose output converts the motor
shaft position into a coded signal. The TCCM must
supply 5VDC (+/- 0.5v) to the sensor and monitor the
shift motor position. The four channels are denoted
A, B, C, and D. The sensor is mechanically linked to
the shaft of the cam which causes the transfer case
shifting. The mode sensor draws less than 53 mA.
OPERATION
During normal vehicle operation, the Transfer Case
Control Module (TCCM) monitors the mode sensor
outputs at least every 250 (+/-50) milliseconds when
the shift motor is stationary and 400 microseconds
when the shift motor is active. A mode sensor signal
between 3.8 Volts and 0.8 Volts is considered to be
undefined.
Refer to SECTOR ANGLES vs. TRANSFER CASE
POSITION for the relative angles of the transfer case
shift sector versus the interpreted transfer case gear
operating mode. Refer to MODE SENSOR CHAN-
NEL STATES for the sensor codes returned to the
TCCM for each transfer case mode sensor position.
The various between gears positions can also be
referred as the transfer case's coarse position. These
coarse positions come into play during shift attempts.SECTOR ANGLES VS. TRANSFER CASE POSITION
Shaft Angle (Degrees) Transfer Case Position
+40 4LO
+20 N
0 2WD/AWD
-20 4HI
MODE SENSOR CHANNEL STATES
Transfer Case
Angle (degrees)Sensor Channel A Sensor Channel B Sensor Channel C Sensor Channel D
Between Gears H H L H
+40 (4LO) H H L L
Between Gears H H L H
Between Gears H L L H
+20 (NEUTRAL) H L L L
Between Gears H L L H
Between Gears H L H H
0 (2WD/AWD) H L H L
Between Gears H L H H
Between Gears L L H H
-20 (4HI) L L H L
Between Gears L L H H
Between Gears L H H H
Fig. 94 Mode Sensor
1 - MODE SENSOR
DRTRANSFER CASE - NV273 21 - 573

METHOD 1 (RELOCATE WHEEL ON HUB)
(1) Drive vehicle a short distance to eliminate tire
flat spotting from a parked position.
(2) Check wheel bearings and adjust if adjustable
or replace if necessary.
(3) Check the wheel mounting surface.
(4) Relocate wheel on the mounting, two studs
over from the original position.
(5) Tighten wheel nuts until all are properly
torqued, to eliminate brake distortion.
(6) Check radial runout. If still excessive, mark
tire sidewall, wheel, and stud at point of maximum
runout and proceed to Method 2.
METHOD 2 (RELOCATE TIRE ON WHEEL)
NOTE: Rotating the tire on wheel is particularly
effective when there is runout in both tire and
wheel.
(1) Remove tire from wheel and mount wheel on
service dynamic balance machine.
(2) Check wheel radial runout (Fig. 2) and lateral
runout (Fig. 3).
²STEEL WHEELS: Radial runout 0.031 in., Lat-
eral runout 0.031 in. (maximum)
²ALUMINUM WHEELS: Radial runout 0.020 in.,
Lateral runout 0.025 in. (maximum)
(3) If point of greatest wheel lateral runout is near
original chalk mark, remount tire 180 degrees.
Recheck runout, Refer to match mounting procedure.
Fig. 1 Checking Tire/Wheel/Hub Runout
1 - RADIAL RUNOUT
2 - LATERAL RUNOUT
Fig. 2 Radial Runout
1 - MOUNTING CONE
2 - SPINDLE SHAFT
3 - WING NUT
4 - PLASTIC CUP
5 - DIAL INDICATOR
6 - WHEEL
7 - DIAL INDICATOR
Fig. 3 Lateral Runout
1 - MOUNTING CONE
2 - SPINDLE SHAFT
3 - WING NUT
4 - PLASTIC CUP
5 - DIAL INDICATOR
6 - WHEEL
7 - DIAL INDICATOR
22 - 2 TIRES/WHEELSDR
TIRES/WHEELS (Continued)

(3) Break down the tire and remount it 180
degrees on the rim (Fig. 7).
(4) Measure the total indicator runout again. Mark
the tire to indicate the high spot.
(5) If runout is still excessive, the following proce-
dures must be done.
²If the high spot is within 101.6 mm (4.0 in.) of
the first spot and is still excessive, replace the tire.
²If the high spot is within 101.6 mm (4.0 in.) of
the first spot on the wheel, the wheel may be out of
specifications. Refer to Wheel and Tire Runout.
²If the high spot is NOT within 101.6 mm (4.0
in.) of either high spot, draw an arrow on the tread
from second high spot to first. Break down the tire
and remount it 90 degrees on rim in that direction
(Fig. 8). This procedure will normally reduce the
runout to an acceptable amount, if not replace the
rim.
STANDARD PROCEDURE - TIRE AND WHEEL
BALANCE
It is recommended that a two plane service
dynamic balancer be used when a tire and wheel
assembly require balancing. Refer to balancer opera-
tion instructions for proper cone mounting proce-
dures. Typically use front cone mounting method for
steel wheels. For aluminum wheel use back cone
mounting method without cone spring.NOTE: Static should be used only when a two plane
balancer is not available.
NOTE: Cast aluminum and forged aluminum wheels
require coated balance weights and special align-
ment equipment.
Wheel balancing can be accomplished with either
on or off vehicle equipment. When using on-vehicle
balancing equipment, remove the opposite wheel/tire.
Off-vehicle balancing is recommended.
For static balancing, find the location of the heavy
spot causing the imbalance. Counter balance wheel
directly opposite the heavy spot. Determine weight
required to counter balance the area of imbalance.
Place half of this weight on theinnerrim flange and
the other half on theouterrim flange (Fig. 9).
For dynamic balancing, the balancing equipment is
designed to locate the amount of weight to be applied
to both the inner and outer rim flange (Fig. 10).
Fig. 7 Remount Tire 180 Degrees
1 - VALVE STEM
2 - REFERENCE MARK
Fig. 8 Remount Tire 90 Degrees In Direction of
Arrow
1 - 2ND HIGH SPOT ON TIRE
2 - 1ST HIGH SPOT ON TIRE
22 - 4 TIRES/WHEELSDR
TIRES/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)

²Panel repair for both flexible and rigid panels
are basically the same. The primary difference
between flexible panel repair and rigid panel repair
is in the adhesive materials used (Fig. 5).
²The technician should first decide what needs to
be done when working on any type of body panel.
One should determine if it is possible to return the
damage part to its original strength and appearance
without exceeding the value of the replacement part.
²When plastic repairs are required, it is recom-
mended that the part be left on the vehicle when
every possible. That will save time, and the panel
will remain stationary during the repair. Misalign-ment can cause stress in the repair areas and can
result in future failure.
VISUAL INSPECTION
Composite materials can mask the severity of an
accident. Adhesive bond lines, interior structure of
the doors, and steel structures need to be inspected
carefully to get a true damage assessment. Close
inspection may require partial removal of interior
trim or inner panels.
Identify the type of repair: Puncture or Crack -
Damage that has penetrated completely through the
panel. Damage is confined to one general area; a
panel section is not required. However, a backer
panel, open fiberglass tape, or matted material must
be bonded from behind (Fig. 7) (Fig. 6).
PANEL SURFACE PREPARATION
If a body panel has been punctured, cracked, or
crushed, the damaged area must be removed from
the panel to achieve a successful repair. All spider
web cracks leading away from a damaged area must
be stopped or removed. To stop a running crack in a
panel, drilla6mm(0.250 in.) hole at the end of the
crack farthest away from the damage. If spider web
cracks can not be stopped, the panel would require
replacement. The surfaces around the damaged area
Fig. 2 SOFTENED EDGES
1 - SOFTENED EDGES
2 - PANEL ADHESIVE
3 - BONDING STRIP
Fig. 3 PANEL REINFORCEMENT
1 - PANEL ADHESIVE
2 - REINFORCEMENT
Fig. 4 BEVELING ANGLE - 20 DEGREE
Fig. 5 FIBERGLASS TAPE
Fig. 6 DAMAGE COMPONENT
1 - PUNCTURE
DRBODY 23 - 7
BODY (Continued)

should be stripped of paint and freed from wax and
oil. Scuff surfaces around repair area with 360 grit
wet/dry sandpaper, or equivalent, to assure adhesion
of repair materials.
PATCHING PANELS
An panel that has extensive puncture type damage
can be repaired by cutting out the damaged material
(Fig. 7). Use a suitable reciprocating saw or cut off
wheel to remove the section of the panel that is dam-
aged. The piece cut out can be used as a template to
shape the new patch. It is not necessary to have
access to the back of the panel to install a patch.
Bevel edges of cutout at 20 degrees to expose a larger
bonding area on the outer side. This will allow for an
increased reinforcement areas.
PANEL PATCH FABRICATIONS
A patch can be fabricated from any rigid fiberglass
panel that has comparable contour with the repair
area. Lift gates and fenders can be used to supply
patch material. If existing material is not available
or compatible, a patch can be constructed with adhe-
sive and reinforcement mesh (dry wall tape). Perform
the following operation if required:
(1) Cover waxed paper or plastic with adhesive
backed nylon mesh (dry wall tape) larger than the
patch required (Fig. 8).(2) Tape waxed paper or plastic sheet with mesh to
a surface that has a compatible contour to the repair
area.
(3) Apply a liberal coat of adhesive over the rein-
forcement mesh (Fig. 8). If necessary apply a second
or third coat of adhesive and mesh after first coat
has cured. The thickness of the patch should be the
same as the repair area.
(4) After patch has cured, peel waxed paper or
plastic from the back of the patch.
(5) If desired, a thin film coat of adhesive can be
applied to the back of the patch to cover mesh for
added strength.
PANEL PATCH INSTALLATION
(1) Make a paper or cardboard pattern the size
and shape of the cutout hole in the panel.
(2) Trim 3 mm (0.125 in.) from edges of pattern so
patch will have a gap between connecting surfaces.
(3) Using the pattern as a guide, cut the patch to
size.
(4) Cut scrap pieces of patch material into 50 mm
(2 in.) squares to use as patch supports to sustain
the patch in the cutout.
(5) Drill 4 mm (0.160 in.) holes 13 mm (0.5 in.) in
from edge of cutout hole (Fig. 7).
(6) Drill 4 mm (0.160 in.) holes 13 mm (0.5 in.)
away from edge of patch across from holes drilled
around cutout.
Fig. 7 DAMAGED PANEL CUTOUT AND PATCH
1 - CUTOUT
2 - DAMAGED BODY PANEL
3-4MM(0.160 IN.) HOLES
4 - PATCH CUT TO SIZE
Fig. 8 FABRICATED PANEL
1 - STRUCTURAL ADHESIVE
2 - FIBERGLASS CLOTH OR FIBERGLASS MESH TAPE
3 - WIDTH OF V-GROOVE
4 - WAXED PAPER
23 - 8 BODYDR
BODY (Continued)

WINDSHIELD
WARNING
WINDSHIELD SAFETY PRECAUTIONS
WARNING: DO NOT OPERATE THE VEHICLE
WITHIN 24 HOURS OF WINDSHIELD INSTALLATION.
IT TAKES AT LEAST 24 HOURS FOR URETHANE
ADHESIVE TO CURE. IF IT IS NOT CURED, THE
WINDSHIELD MAY NOT PERFORM PROPERLY IN
AN ACCIDENT.
²URETHANE ADHESIVES ARE APPLIED AS A
SYSTEM. USE GLASS CLEANER, GLASS PREP
SOLVENT, GLASS PRIMER, PVC (VINYL) PRIMER
AND PINCH WELD (FENCE) PRIMER PROVIDED BY
THE ADHESIVE MANUFACTURER. IF NOT, STRUC-
TURAL INTEGRITY COULD BE COMPROMISED.
²DAIMLERCHRYSLER DOES NOT RECOMMEND
GLASS ADHESIVE BY BRAND. TECHNICIANS
SHOULD REVIEW PRODUCT LABELS AND TECHNI-
CAL DATA SHEETS, AND USE ONLY ADHESIVES
THAT THEIR MANUFACTURES WARRANT WILL
RESTORE A VEHICLE TO THE REQUIREMENTS OF
FMVSS 212. TECHNICIANS SHOULD ALSO INSURE
THAT PRIMERS AND CLEANERS ARE COMPATIBLE
WITH THE PARTICULAR ADHESIVE USED.
²BE SURE TO REFER TO THE URETHANE MAN-
UFACTURER'S DIRECTIONS FOR CURING TIME
SPECIFICATIONS, AND DO NOT USE ADHESIVE
AFTER ITS EXPIRATION DATE.
²VAPORS THAT ARE EMITTED FROM THE URE-
THANE ADHESIVE OR PRIMER COULD CAUSE
PERSONAL INJURY. USE THEM IN A WELL-VENTI-
LATED AREA.
²SKIN CONTACT WITH URETHANE ADHESIVE
SHOULD BE AVOIDED. PERSONAL INJURY MAY
RESULT.
²ALWAYS WEAR EYE AND HAND PROTECTION
WHEN WORKING WITH GLASS.
CAUTION: Protect all painted and trimmed surfaces
from coming in contact with urethane or primers.
Be careful not to damage painted surfaces when
removing moldings or cutting urethane around
windshield.
REMOVAL
(1) Remove inside rear view mirror. (Refer to 23 -
BODY/INTERIOR/REAR VIEW MIRROR -
REMOVAL).
(2) Remove cowl grill. (Refer to 23 - BODY/EXTE-
RIOR/COWL GRILLE - REMOVAL).(3) Remove the a-pillar weatherstrip retainer.
(Refer to 23 - BODY/WEATHERSTRIP/SEALS/A-
PILLAR WEATHERSTRIP RETAINER - REMOVAL)
(4) Remove the a-pillar trim panels. (Refer to 23 -
BODY/INTERIOR/A-PILLAR TRIM - REMOVAL)
(5) Remove the headliner and from the inside of
the vehicle, cut the upper urethane bonding from
around windshield upper edge using a suitable sharp
cold knife (C-4849). A pneumatic cutting device can
be used but is not recommended. (Refer to 23 -
BODY/INTERIOR/HEADLINER - REMOVAL)
(6) From the outside of the vehicle, cut urethane
bonding from the remaining sides of the windshield
using a suitable sharp cold knife (C-4849). A pneu-
matic cutting device can be used but is not recom-
mended.
(7) Separate windshield from vehicle.
INSTALLATION
WARNING: Allow the urethane at least 24 hours to
cure before returning the vehicle to use.
CAUTION: Roll down the left and right front door
glass and open the rear glass slider (if available)
before installing windshield to avoid pressurizing
the passenger compartment if a door is slammed
before urethane is cured. Water leaks can result.
The windshield fence should be cleaned of most of
its old urethane bonding material. A small amount of
old urethane, approximately 1-2 mm in height,
should remain on the fence. Do not grind off or com-
pletely remove all old urethane from the fence, the
paint finish and bonding strength will be adversely
affected.
(1) Place replacement windshield into windshield
opening and position glass in the center of the open-
ing against the support spacers. Mark the outside
surface of the glass at the support spacers with a
grease pencil or pieces of masking tape and ink pen
to use as a reference for installation. Remove replace-
ment windshield from windshield opening (Fig. 5).
(2) Position the windshield inside up on a suitable
work surface with two padded, wood 10 cm by 10 cm
by 50 cm (4 in. by 4 in. by 20 in.) blocks, placed par-
allel 75 cm (2.5 ft.) apart (Fig. 6).
(3) Clean inside of windshield with MOPAR Glass
Cleaner and lint-free cloth.
(4) Apply clear glass primer 25 mm (1 in.) wide
around perimeter of windshield and wipe with a new
clean and dry lint- free cloth.
(5) Apply black-out primer onto the glass using the
windshield molding as a guide. The primer should be
15 mm (5/8 in.) wide on the top and sides of the glass
23 - 88 STATIONARY GLASSDR

ber above the heating, ventilation and air condition-
ing (HVAC) housing. On models equipped with air
conditioning, the air passes through the evaporator
coil. Air flow can be directed either through or
around the heater core. This is done by adjusting the
blend door with the temperature control knob on the
A/C-heater control located the instrument panel. The
air flow can then be directed from the panel, floor
and defrost outlets in various combinations using the
mode control knob located on the A/C-heater control.
Air flow velocity can be adjusted with the blower
speed selector located on the A/C-heater control.
NOTE: It is important to keep the air intake opening
clear of debris. Leaf particles and other debris that
is small enough to pass through the cowl opening
screen can accumulate within the HVAC housing.
The closed, warm, damp and dark environment cre-
ated within the housing is ideal for the growth of
certain molds, mildews and other fungi. Any accu-mulation of decaying plant matter provides an addi-
tional food source for fungal spores, which enter
the housing with the fresh intake-air. Excess debris,
as well as objectionable odors created by decaying
plant matter and growing fungi can be discharged
into the passenger compartment during heater-A/C
operation if the air intake opening is not kept clear
of debris.
The heater and air conditioning systems are blend-
air type systems. In a blend-air system, a blend door
controls the amount of unconditioned air (or cooled
air from the evaporator on models with air condition-
ing) that is allowed to flow through, or around, the
heater core. A temperature control knob determines
the discharge air temperature by actuating an elec-
tric motor, which operates the blend door. This allows
an almost immediate control of the output air tem-
perature of the system.
On all models, the outside air intake can be shut
off by selecting the Recirculation Mode with the
mode control knob. This will operate a electric actu-
ated recirculation air door that closes off the outside
fresh air intake and recirculates the air that is
already inside the vehicle.
The air conditioning compressor can be engaged in
any mode by pressing the snowflake, A/C on/off but-
ton. It can also be engaged by placing the mode con-
trol in the mix to defrost positions. This will remove
heat and humidity from the air before it is directed
through or around the heater core. The mode control
knob on the A/C-heater control is used to also direct
the conditioned air to the selected system outlets.
The mode control switch uses an electric motor to
control the mode doors.
The defroster outlet receives airflow from the
HVAC housing through the molded plastic defroster
duct, which connects to the HVAC housing defroster
outlet. The airflow from the defroster outlets is
directed by fixed vanes in the defroster outlet grilles
and cannot be adjusted. The defroster outlet grilles
are integral to the instrument panel top cover.
The side window demister outlets receive airflow
from the HVAC housing through the molded plastic
defroster duct and two molded plastic demister ducts.
The airflow from the side window demister outlets is
directed by fixed vanes in the demister outlet grilles
and cannot be adjusted. The side window demister
outlet grilles are integral to the instrument panel.
The demisters direct air from the HVAC housing
through the outlets located on the top corners of the
instrument panel. The demisters operate when the
mode control knob is positioned in the floor-defrost
and defrost-only settings. Some air may be noticeable
from the demister outlets when the mode control is
in the bi-level to floor positions.
Fig. 1 HVAC Housing - Dual Zone Shown, Single
Zone Typical
1 - NUT
2 - PASSENGER BLEND DOOR ACTUATOR
3 - NUT
4 - INLET BAFFLE
5 - RECIRCULATION DOOR ACTUATOR
6 - RECIRCULATION DOOR
7 - DRIVER SIDE BLEND DOOR ACTUATOR
8 - HVAC HOUSING
9 - BOLT
10 - DEFROSTER DOOR ACTUATOR
11 - MODE DOOR ACTUATOR
24 - 2 HEATING & AIR CONDITIONINGDR
HEATING & AIR CONDITIONING (Continued)