trailer DODGE RAM 2003 Service Owner's Manual

TRAILER TOW CONNECTOR-4WAY
CAV CIRCUIT FUNCTION
1 Z52 14BK GROUND
2 L76 18BK/OR PARK LAMP RELAY OUTPUT
3 Y141 18YL/PK TRAILER TOW LEFT TURN RELAY OUTPUT
4 Y140 18WT/PK TRAILER TOW RIGHT TURN RELAY OUTPUT
TRAILER TOW CONNECTOR-ADD ON - 10 WAY
CAV CIRCUIT FUNCTION
1- -
2 Y140 18WT/PK TRAILER TOW RIGHT TURN RELAY OUTPUT
3 L1 18VT/BK BACKUP LAMP FEED
4 Y133 14WT/RD FUSED B(+)
5 L76 18BK/OR PARK LAMP RELAY OUTPUT
6- -
7 B40 14LB TRAILER TOW BRAKE B(+)
8 Z52 14BK GROUND
9 Z52 14BK GROUND
10 Y141 18YL/PK TRAILER TOW LEFT TURN RELAY OUTPUT
TRANSFER CASE CONTROL MODULE C1 - BLACK 16 WAY
CAV CIRCUIT FUNCTION
A1 D25 20VT/DB PCI BUS
A2 - -
A3 - -
A4 Y122 20DG/BR 4WD LOW INDICATOR
A5 Y123 20DG/OR 4WD HIGH INDICATOR
A6 Y120 20YL/DG MODE SELECT
A7 Y116 20YL/GY MODE SENSOR GROUND
A8 Z366 18BK/RD GROUND
B1 - -
B2 - -
B3 - -
B4 Y121 20YL/LG NEUTRAL INDICATOR
B5 Y187 20RD 2WD/AWD INDICATOR
B6 Y112 20YL/BR MODE SENSOR D
B7 - -
B8 Z114 20LG/BK SENSOR GROUND
DR8W-80 CONNECTOR PIN-OUTS 8W - 80 - 101

CONNECTOR NAME/NUMBER COLOR LOCATION FIG.
Speed Control Switch-Right (ETC) WT At Steering Wheel N/S
Tail/Stop/Turn Signal Lamp-Left BK At Lamp N/S
Tail/Stop/Turn Signal Lamp-Right BK At Lamp N/S
Throttle Position Sensor NAT Throttle Body 4, 8
Trailer Tow Connector BK At Trailer Hitch 49
Trailer Tow Connector-Add On BK At Trailer Hitch 49, 51
Transfer Case Control Module C1 BK Left Side of Instrument Panel 37, 39
Transfer Case Control Module C2 GY Left Side of Instrument Panel 37, 39
Transfer Case Control Module C3 BK Left Side of Instrument Panel 37, 39
Transfer Case Mode Sensor BK Left Front Side of Transfer Case 20
Transfer Case Position Sensor BK Front Middle of Transfer Case 14, 15, 16, 20
Transfer Case Selector Switch BK Center of Instrument Panel 35, 37, 38
Transfer Case Shift Motor BK Left Rear of Transmission 20
Transmission Control Module BK Left Rear of Engine Compartment 21
Transmission Range Sensor BK Left side of Transmission 11, 12
Transmission Solenoid Assembly BK Left Side of Transmission 11, 12
Transmission Solenoid/TRS
Assembly (3.7L/4.7L)BK Left Side of Transmission 14, 15
Underhood Lamp BK Underside of Hood 31
Vistronic Fan Drive Front Engine Compartment 30
Washer Fluid Level Switch BK At Reservoir 25, 29, 30
Washer Pump Motor-Front BK At Washer Fluid Reservoir 25, 29, 30
Water In Fuel Sensor (Diesel) BK Right Side Engine 10
Wheel Speed Sensor-Left Front BK Left Rear Lower Side of Engine
Compartment26, 31
Wheel Speed Sensor-Rear BK Right Rear of Body 49
Wheel Speed Sensor-Right Front GY Right Rear Lower Side of Engine
Compartment25
Wiper Motor-Front BK Left Side of Cowl 26, 28
8W - 91 - 8 8W-91 CONNECTOR/GROUND/SPLICE LOCATIONDR
CONNECTOR/GROUND/SPLICE LOCATION (Continued)

FRAMES & BUMPERS
TABLE OF CONTENTS
page page
BUMPERS
SPECIFICATIONS - TORQUE...............1
FRONT AIR DAM
REMOVAL.............................2
INSTALLATION..........................2
FRONT BUMPER
REMOVAL.............................2
INSTALLATION..........................2
FRONT FASCIA
REMOVAL.............................3
INSTALLATION..........................3
REAR BUMPER
REMOVAL.............................4
INSTALLATION..........................4
FRAME
STANDARD PROCEDURE
STANDARD PROCEDURE - LIGHT DUTY
FRONT FRAME RAIL TIP REPLACEMENT....4
STANDARD PROCEDURE - HYDROFORM
FENDER RAIL REPAIR.................12
STANDARD PROCEDURE - REAR FRAME
H-SECTION REPLACEMENT.............15SPECIFICATIONS
SPECIFICATIONS - FRAME DIMENSIONS . . . 17
SPECIFICATIONS - TORQUE............23
FRONT CROSSMEMBER
REMOVAL.............................23
INSTALLATION.........................23
FRONT SKID PLATE
REMOVAL.............................24
INSTALLATION.........................24
TRANSMISSION CROSSMEMBER
REMOVAL.............................24
INSTALLATION.........................25
TRAILER HITCH
REMOVAL.............................25
INSTALLATION.........................25
TRANSFER CASE SKID PLATE
REMOVAL.............................26
INSTALLATION.........................26
FRONT TOW HOOK ASSEMBLY
REMOVAL.............................26
INSTALLATION.........................26
BUMPERS
SPECIFICATIONS - TORQUE
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Front bumper center bracket nuts 95 70 Ð
Front bumper stud plate nuts 95 70 Ð
License plate hitch reinforcement bolts 54 40 Ð
Rear bumper support bracket stud plate nuts 54 40 Ð
Rear bumper support bracket to hitch bolts 54 40 Ð
Rear bumper to hitch bolts 54 40 Ð
DRFRAMES & BUMPERS 13 - 1

REAR BUMPER
REMOVAL
(1) Raise and support the vehicle. (Refer to
LUBRICATION & MAINTENANCE/HOISTING -
STANDARD PROCEDURE)
(2) Remove the license plate.
(3) Remove the bolts behind the plate.
(4) Disconnect the license plate light electrical con-
nectors.
(5) Disconnect the trailer light connector electrical
connection, if equipped.
(6) Remove the two bolts along the front upper
edge of the bumper near the frame tips.
(7)
Support the bumper with a suitable lifting device.
(8) Remove the bolts attaching the bumper support
brackets to the trailer hitch. (Fig. 5)
INSTALLATION
(1) Align the holes in the bumpers to the trailer
hitch pins and install the bumper.
(2) Install the support bracket to the hitch bolts,
loosely.
(3) Install the front upper edge to the trailer hitch
bolts and tighten to 54 N´m (40 ft. lbs.).
(4) Install the license plate reinforcement to hitch
bolts and tighten to 54 N´m (40 ft. lbs.).
(5) Tighten the left bumper bracket bolts to 54
N´m (40 ft. lbs.).
(6) Tighten the right bumper bracket bolts to 54
N´m (40 ft. lbs.).
(7) Connect the trailer light connector electrical
connection, if equipped.
(8) Connect the license plate light electrical con-
nectors.
(9) Install the license plate.
FRAME
STANDARD PROCEDURE
STANDARD PROCEDURE - LIGHT DUTY FRONT
FRAME RAIL TIP REPLACEMENT
SAFETY PRECAUTIONS AND WARNINGS
WARNING: USE EYE PROTECTION WHEN GRIND-
ING OR WELDING METAL, SERIOUS EYE INJURY
CAN RESULT.
²BEFORE PROCEEDING WITH FRAME REPAIR
INVOLVING GRINDING OR WELDING, VERIFY THAT
VEHICLE FUEL SYSTEM IS NOT LEAKING OR IN
CONTACT WITH REPAIR AREA, PERSONAL INJURY
CAN RESULT.
²DO NOT ALLOW OPEN FLAME OR HEAT AND
METAL SPATTER FROM ARC WELDING, TO CON-
TACT PLASTIC BODY PANELS. FIRE OR EXPLO-
SION CAN RESULT.
²WHEN WELDED FRAME COMPONENTS ARE
REPLACED, ENSURE COMPLETE PENETRATION
WELD IS ACHIEVED DURING INSTALLATION. IF
NOT, DANGEROUS OPERATING CONDITIONS CAN
RESULT.
²STAND CLEAR OF CABLES OR CHAINS ON
PULLING EQUIPMENT DURING FRAME STRAIGHT-
ENING OPERATIONS, PERSONAL INJURY CAN
RESULT.
²DO NOT VENTURE UNDER A HOISTED VEHI-
CLE THAT IS NOT SUPPORTED ON SAFETY
STANDS, PERSONAL INJURY CAN RESULT.
CAUTION: 1500 series Dodge Ram Trucks (2002 and
later) are not designed for snow plow equipment.
The front collision repair tips must not be installed
on any truck equipped with a snow plow, or even
intended to be equipped with a snow plow.
CAUTION: This procedure is designed to replace
the front frame rail tips that have been damaged in
the crush initiator zones. Prior to any cutting, the
vehicle must be mounted on the appropriate frame
repair equipment (ªframe rackº), checked with three
dimensional measuring equipment, and the neces-
sary pull corrections made. If damage remains in
the frame beyond the area covered by this service
part after the pull, the frame must be replaced in its
entirety.
Fig. 5 TRAILER HITCH
1 - HITCH
2 - HITCH BOLTS (4)
3 - BUMPER BRACKET BOLTS (4)
4 - BUMPER SUPPORT BRACKETS
13 - 4 FRAMES & BUMPERSDR

STANDARD PROCEDURE - REAR FRAME
H-SECTION REPLACEMENT
SAFETY PRECAUTIONS AND WARNINGS
WARNING: USE EYE PROTECTION WHEN GRIND-
ING OR WELDING METAL, SERIOUS EYE INJURY
CAN RESULT.
²BEFORE PROCEEDING WITH FRAME REPAIR
INVOLVING GRINDING OR WELDING, VERIFY THAT
VEHICLE FUEL SYSTEM IS NOT LEAKING OR IN
CONTACT WITH REPAIR AREA, PERSONAL INJURY
CAN RESULT.
²DO NOT ALLOW OPEN FLAME OR HEAT AND
METAL SPATTER FROM ARC WELDING, TO CON-
TACT PLASTIC BODY PANELS. FIRE OR EXPLO-
SION CAN RESULT.
²WHEN WELDED FRAME COMPONENTS ARE
REPLACED, ENSURE COMPLETE PENETRATION
WELD IS ACHIEVED DURING INSTALLATION. IF
NOT, DANGEROUS OPERATING CONDITIONS CAN
RESULT.
²STAND CLEAR OF CABLES OR CHAINS ON
PULLING EQUIPMENT DURING FRAME STRAIGHT-
ENING OPERATIONS, PERSONAL INJURY CAN
RESULT.
²DO NOT VENTURE UNDER A HOISTED VEHI-
CLE THAT IS NOT SUPPORTED ON SAFETY
STANDS, PERSONAL INJURY CAN RESULT.
CAUTION: Do not reuse damaged fasteners, quality
of repair would be suspect. Failure to use only pro-
duction fasteners or fasteners of equivalent hard-
ness can result in loosening or failure. Do not drill
holes in top or bottom frame rail flanges, frame rail
failure can result. When using heat to straighten
frame components do not exceed 566ÉC (1050ÉF),
metal fatigue can result.
CAUTION: This procedure is designed to replace
the H-section/spare tire support located at the rear
of the frame assembly. Prior to any cutting, the
vehicle must be mounted on the appropriate frame
repair equipment (ªframe rackº), checked with three
dimensional measuring equipment, and the neces-
sary pull corrections made. If damage remains in
the frame beyond the area covered by this service
part after the pull, the frame must be replaced in its
entirety.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cargo box. (Refer to 23 - BODY/EX-
TERIOR/CARGO BOX - REMOVAL)(3) Remove the trailer hitch. (Refer to 13 - FRAME
& BUMPERS/FRAME/TRAILER HITCH -
REMOVAL)
(4) Raise and support the frame so the tires are off
floor.
(5) Remove the shock absorbers. (Refer to 2 - SUS-
PENSION/REAR/SHOCK - REMOVAL)
(6) Remove the rear leaf spring shackle bolts and
let the axle rest on the ground. (Fig. 21)
(7) Remove the spare wheel.
(8) Remove the clip and remove the spare tire
winch tube. (Fig. 22)
Fig. 21 REAR SPRING
1 - SPRING SHACKLE
2 - LEAF SPRING EYE BOLT/NUT
3 - REAR LEAF SPRING
Fig. 22 SPARE TIRE WINCH TUBE
1 - SPARE TIRE WINCH ASSEMBLY
2 - HAIR PIN CLIP
3 - WINCH TUBE
4 - H-SECTION/SPARE WHEEL SUPPORT
DRFRAMES & BUMPERS 13 - 15
FRAME (Continued)

(9) Remove the bolts and remove the spare tire
winch. (Fig. 23)
(10) Position the wire harness forward of the work
area.
CAUTION: Do not use any flame or plasma cutting
equipment to cut the frame in this procedure. The
inaccurate and high temperatures achieved during
flame or plasma cutting will change the metal char-
acteristics and may weaken the frame and/or repair
location.
(11) Carefully remove the H-section welds using a
grinder or equivalent tool.
(12) Remove the H-section and clean any remain-
ing welds from the frame.
(13) Trial fit the replacement part.
(14) Remove all e-coat from within 25 mm (1.0 in.)
of the weld area.
(15) Using the appropriate measuring equipment,
position the replacement part and verify correct posi-
tioning in all three (X,Y, and Z) planes of space.(Refer to 13 - FRAME & BUMPERS/FRAME - SPEC-
IFICATIONS - FRAME DIMENSIONS)
CAUTION: Shield the surrounding area and compo-
nents from exposure to the welding spatter and
heat.
(16) Weld the replacement H-section into position.
The welding should be performed in a skip (stitch)
type method to minimize the heat buildup following
I-CAR or the American Welding Society welding pro-
cedures and utilizing the process specifications at the
end of this section. Refer to the Weld Process Speci-
fications welding schedule below.
(17) Dress the welded area and apply corrosion
resistant coatings inside and out.
(a) Inside the rail, inject a creeping wax based
rust inhibitor compound through the existing holes
in the frame ensuring 100% coverage including the
mating face between the frame and replacement
H-section.
(b) Apply a durable top coat to the outside of the
repair area.
(18) Position the wiring harness back.
(19) Install the spare tire winch and install the
bolts. (Fig. 23)
(20) Tighten the bolts to 41 N´m (30 ft. lbs.).
(21) Install the spare tire winch tube and install
the clip. (Fig. 22)
(22) Install the spare tire.
(23) Lift the axle into position and install the rear
shackle bolts. (Fig. 21)
(24) Tighten the bolts to 163 N´m (120 ft. lbs.).
(25) Install the lower shock absorber bolts. (Refer
to 2 - SUSPENSION/REAR/SHOCK - INSTALLA-
TION)
(26) Install the trailer hitch. (Refer to 13 - FRAME
& BUMPERS/FRAME/TRAILER HITCH - INSTAL-
LATION)
(27) Install the cargo box. (Refer to 23 - BODY/EX-
TERIOR/CARGO BOX - INSTALLATION)
(28) Reconnect the battery ground.
Fig. 23 SPARE TIRE WINCH ASSEMBLY
1 - SPARE TIRE WINCH ASSEMBLY
2 - BOLTS
3 - RETAINER BRACKET
4 - H-SECTION/SPARE WHEEL SUPPORT
13 - 16 FRAMES & BUMPERSDR
FRAME (Continued)

SPECIFICATIONS - TORQUE
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Cab mount bolts 81 60 Ð
Cargo box bolts 108 80 Ð
Front crossmember bolts - 2WD 61 45 Ð
Front crossmember bolts - 4WD 102 75 Ð
Front skid plate bolts 34 25 Ð
Lower bumper support bracket bolt 54 40 Ð
Radiator crossmember bolts - lower 28 21 Ð
Radiator crossmember bolts - upper 28 21 Ð
Rear crossmember - 2WD 102 75 Ð
Rear crossmember - 4WD 102 75 Ð
Rear spring shackle bolts 163 120 Ð
Spare tire winch bolts 41 30 Ð
Trailer hitch reinforcement bracket bolt 170 125 Ð
Transfercase skid plate bolts 34 25 Ð
Transercase skid plate crossmember bolts 34 25 Ð
Transmission mount to crossmember nuts 61 45 Ð
FRONT CROSSMEMBER
REMOVAL
(1) Raise and support the vehicle. (Refer to
LUBRICATION & MAINTENANCE/HOISTING -
STANDARD PROCEDURE)
(2) Remove the front skid plate, if equipped. (Refer
to 13 - FRAME & BUMPERS/FRAME/FRONT SKID
PLATE - REMOVAL)
(3) Remove the bolts and remove the crossmember.
(Fig. 29) or (Fig. 30)
INSTALLATION
(1) Install the crossmember.
(2) Install the bolts;
²On 2WD vehicles, tighten the bolts to 61 N´m
(45 ft. lbs.).
²On 4WD vehicles, tighten the bolts to 102 N´m
(75 ft. lbs.).
Fig. 29 FRONT CROSSMEMBER - 2WD
1 - CROSSMEMBER
2 - BOLTS (2 PER SIDE)
DRFRAMES & BUMPERS 13 - 23
FRAME (Continued)

INSTALLATION
(1) Install the crossmember and install the bolts.
(2) Tighten the bolts to 102 N´m (75 ft. lbs.).
(3) Install the transmission mount nuts and
tighten to 61 N´m (45 ft. lbs.).
(4) Remove the transmission support.
(5) Install the transfercase skid plate. (Refer to 13
- FRAME & BUMPERS/FRAME/TRANSFER CASE
SKID PLATE - INSTALLATION)
TRAILER HITCH
REMOVAL
(1) Remove the rear bumper. (Refer to 13 -
FRAME & BUMPERS/BUMPERS/REAR BUMPER -
REMOVAL)
(2) Remove the hitch bolts. (Fig. 34)
(3) Disconnect all wire harness support push pins.(4) Remove the rear two cargo box bolts and loosen
the remaining bolts. (Refer to 23 - BODY/EXTERI-
OR/CARGO BOX - REMOVAL)
(5) Using a suitable lifting device, lift and support
the rear of the cargo box and remove the hitch.
INSTALLATION
(1) Install the hitch onto the frame rails and make
sure the locators on the inside of the hitch brackets
are engaged with the holes in the top of the frame
rails properly.
(2) Lower the cargo box and install the rear bolts.
(Refer to 23 - BODY/EXTERIOR/CARGO BOX -
INSTALLATION)
(3) Install the hitch bolts and tighten to 170 N´m
(125 ft. lbs.).
(4) Connect all wire harness support push pins.
(5) Install the rear bumper. (Refer to 13 - FRAME
& BUMPERS/BUMPERS/REAR BUMPER - INSTAL-
LATION)
Fig. 33 REAR CROSSMEMBER - 4WD
1 - TRANSMISSION MOUNT
2 - TORSION BAR
3 - CROSSMEMBER BOLTS (3 PER SIDE)
4 - REAR CROSSMEMBER
5 - TRANSMISSION MOUNT NUTS (2)
Fig. 34 TRAILER HITCH
1 - HITCH
2 - HITCH BOLTS (4)
3 - BUMPER BRACKET BOLTS (4)
4 - BUMPER SUPPORT BRACKETS
DRFRAMES & BUMPERS 13 - 25
TRANSMISSION CROSSMEMBER (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 two primary causes.
(1) 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.
(2) 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
repair
The use of non-recommended fluids can result in
transmission failure. The usual results are erratic
shifts, slippage, abnormal wear and eventual failuredue 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 be replaced whenever
a failure generates sludge and debris. This is neces-
sary because normal converter flushing procedures
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.
Fluid level is checked with the engine running at
curb idle speed, the transmission in NEUTRAL and
the transmission fluid at normal operating tempera-
ture.The engine should be running at idle
speed for at least one minute, with the vehicle
on level ground.
The transmission fluid level can be checked two
ways.
PROCEDURE ONE
(1) Transmission fluid must be at normal operat-
ing temperature for accurate fluid level check. Drive
DRAUTOMATIC TRANSMISSION - 46RE 21 - 201

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 two primary causes.
(1) 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.
(2) 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
repair
The use of non-recommended fluids can result in
transmission failure. The usual results are erratic
shifts, slippage, abnormal wear and eventual failuredue 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 be replaced whenever
a failure generates sludge and debris. This is neces-
sary because normal converter flushing procedures
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.
Fluid level is checked with the engine running at
curb idle speed, the transmission in NEUTRAL and
the transmission fluid at normal operating tempera-
ture.The engine should be running at idle
speed for at least one minute, with the vehicle
on level ground.
The transmission fluid level can be checked two
ways.
PROCEDURE ONE
(1) Transmission fluid must be at normal operat-
ing temperature for accurate fluid level check. Drive
DRAUTOMATIC TRANSMISSION - 48RE 21 - 381