2003 DODGE RAM towing

Fan speed is monitored by the ECM. A lack of fan
speed will set a DTC. Circuit concerns will also set
fan clutch DTC's.
Fan speed and duty cycle percent can be monitored
with the DRB III..
DIAGNOSIS AND TESTING - ELECTRONICLY
CONTOLLED VISCOUS FAN DRIVE
NOISE
NOTE: It is normal for fan noise to be louder (roar-
ing) when:
²Fan duty cycle high. This may occur when ambi-
ent (outside air temperature) is very high.
²Engine loads and temperatures are high such as
when towing a trailer.
²Cool silicone fluid within the fan drive unit is
being redistributed back to its normal disengaged
(warm) position. This can occur during the first 15
seconds to one minute after engine start-up on a cold
engine.
LEAKS
Viscous fan drive operation is not affected by small
oil stains near the drive bearing. If leakage appears
excessive, replace the fan drive unit.
ELECTRONICALLY CONTROLLED VISCOUS DRIVE
If the fan assembly free-wheels without drag (the
fan blades will revolve more than five turns when
spun by hand), replace the fan drive. This spin test
must be performed when the engine is cool.
For the following test, the cooling system must be
in good condition. It also will ensure against exces-
sively high coolant temperature.
The Electronic Viscous Fan drive can be tested
using the DRB III scan tool.
(1) Set the parking brake and verify the transmis-
sion is in park or neutral.
(2) Stat and allow engine to reach normal operat-
ing termeratures.
(3) With engine idling, connect the DRB III and
select appropraite model year and engine option.
(4) Lacate and select actuator tests, then select
PWM Viscous Fan.
(5) Monitor fan speed and duty cycle; verify that
the fan speed increments are proportional to the duty
cycle precentage during the actuation event.
CAUTION: Some engines equipped with serpentine
drive belts have reverse rotating fans and viscous
fan drives. They are marked with the word
REVERSE to designate their usage. Installation of
the wrong fan or viscous fan drive can result in
engine overheating.
CAUTION: If the viscous fan drive is replaced
because of mechanical damage, the cooling fan
blades should also be inspected. Inspect for fatigue
cracks, loose blades, or loose rivets that could
have resulted from excessive vibration. Replace fan
blade assembly if any of these conditions are
found.
RADIATOR
DESCRIPTION
The radiator is a aluminum cross-flow design with
horizontal tubes through the radiator core and verti-
cal plastic side tanks (Fig. 32).
This radiator does not contain an internal trans-
mission oil cooler
OPERATION
The radiator supplies sufficient heat transfer using
the cooling fins interlaced between the horizontal
tubes in the radiator core to cool the engine.
Fig. 31 Fan Blade/Viscous Fan Drive
1 - ELECTRICAL CONNECTOR
2 - VISCOUS FAN DRIVE
3 - FAN BLADE
4 - BOLT
5 - FAN DRIVE
7 - 56 ENGINEDR
FAN DRIVE VISCOUS CLUTCH - 5.9L DIESEL (Continued)

layer of the overlay causes the icon to appear in red
through the translucent outer layer of the overlay
when the indicator is illuminated from behind by the
LED, which is soldered onto the instrument cluster
electronic circuit board. The ETC indicator is ser-
viced as a unit with the instrument cluster.
OPERATION
The Electronic Throttle Control (ETC) indicator
gives an indication to the vehicle operator when the
ETC system is faulty or inoperative. The ETC indi-
cator is controlled by a transistor on the instrument
cluster circuit board based upon cluster programming
and electronic messages received by the cluster from
the Powertrain Control Module (PCM) over the Pro-
grammable Communications Interface (PCI) data
bus. The ETC indicator Light Emitting Diode (LED)
is completely controlled by the instrument cluster
logic circuit, and that logic will only allow this indi-
cator to operate when the instrument cluster receives
a battery current input on the fused ignition switch
output (run-start) circuit. Therefore, the LED will
always be off when the ignition switch is in any posi-
tion except On or Start. The LED only illuminates
when it is provided a path to ground by the instru-
ment cluster transistor. The instrument cluster will
turn on the ETC indicator for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the ETC indicator is illu-
minated for about six seconds. The entire six second
bulb test is a function of the PCM.
²ETC Lamp-On Message- Each time the clus-
ter receives a lamp-on message from the PCM, the
ETC indicator will be illuminated. The indicator can
be flashed on and off, or illuminated solid, as dic-
tated by the PCM message. The indicator remains
illuminated solid or continues to flash for about
twelve seconds or until the cluster receives a lamp-off
message from the PCM, whichever is longer. If the
indicator is illuminated solid with the engine run-
ning the vehicle will usually remain drivable. If the
indicator is flashing with the engine running the
vehicle may require towing. A flashing indicator
means the ETC system requires immediate service.
²Communication Error- If the cluster receives
no ETC lamp messages for three consecutive seconds,
the ETC indicator is illuminated. The indicator
remains illuminated until the cluster receives a sin-
gle lamp-off message from the PCM.
²Actuator Test- Each time the cluster is put
through the actuator test, the ETC indicator will be
turned on, then off again during the bulb check por-
tion of the test to confirm the functionality of the
LED and the cluster control circuitry. The actuator
test illumination of the ETC indicator is a function of
the PCM.The PCM continually monitors the ETC system cir-
cuits and sensors to decide whether the system is in
good operating condition. The PCM then sends the
proper lamp-on or lamp-off messages to the instru-
ment cluster. If the PCM sends a lamp-on message
after the bulb test, it indicates that the PCM has
detected a system malfunction and/or that the ETC
system is inoperative. The PCM will store a Diagnos-
tic Trouble Code (DTC) for any malfunction it
detects. Each time the ETC indicator fails to illumi-
nate due to an open or short in the cluster ETC indi-
cator circuit, the cluster sends a message notifying
the PCM of the condition, the instrument cluster and
the PCM will each store a DTC. For proper diagnosis
of the ETC system, the PCM, the PCI data bus, or
the electronic message inputs to the instrument clus-
ter that control the ETC indicator, a DRBIIItscan
tool is required. Refer to the appropriate diagnostic
information.
FUEL GAUGE
DESCRIPTION
A fuel gauge is standard equipment on all instru-
ment clusters. The fuel gauge is located in the lower
left quadrant of the instrument cluster, below the
voltage gauge. The fuel gauge consists of a movable
gauge needle or pointer controlled by the instrument
cluster circuitry and a fixed 90 degree scale on the
cluster overlay that reads left-to-right from ªEº (or
Empty) to ªFº (or Full). An International Control and
Display Symbol icon for ªFuelº is located on the clus-
ter overlay, directly below the right end of the gauge
scale. An arrowhead pointed to the left side of the
vehicle is imprinted on the cluster overlay next to the
ªFuelº icon in the fuel gauge to provide the driver
with a reminder as to the location of the fuel filler
access. On vehicles equipped with a diesel engine,
text that specifies ªDIESEL ONLYº is located across
the fuel gauge below the gauge scale, but above the
hub of the gauge needle. The fuel gauge graphics are
black against a white field except for a single red
graduation at the low end of the gauge scale, making
them clearly visible within the instrument cluster in
daylight. When illuminated from behind by the panel
lamps dimmer controlled cluster illumination lighting
with the exterior lamps turned On, the black graph-
ics appear blue and the red graphics still appear red.
The orange gauge needle is internally illuminated.
Gauge illumination is provided by replaceable incan-
descent bulb and bulb holder units located on the
instrument cluster electronic circuit board. The fuel
gauge is serviced as a unit with the instrument clus-
ter.
DRINSTRUMENT CLUSTER 8J - 25
ETC INDICATOR (Continued)

TRAILER TOW WIRING
DESCRIPTION
Vehicles equipped with an optional factory-in-
stalled trailer towing package have a rear body wire
harness that includes an integral trailer tow wiring
take out that connects to a heavy duty, sealed, 7-pin
trailer tow connector located in the rear bumper (Fig.20). This harness includes an adapter harness that
adapts the 7-pin trailer tow connector to a standard,
light-duty, 4-pin trailer tow connector. Refer to the
appropriate wiring information.
TURN LAMP
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the tail lamp unit (Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING - EXTERIOR/TAIL
LAMP UNIT - REMOVAL).
(3) Remove the bulb back plate from the tail lamp
unit.
(4) Separate the bulb from the lamp bar.
INSTALLATION
(1) Install the bulb into the back plate.
(2) Install the bulb back plate to the tail lamp
unit.
(3) Install the tail lamp unit (Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING - EXTERIOR/TAIL
LAMP UNIT - INSTALLATION).
(4) Connect the negative battery cable.
UNDERHOOD LAMP
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Insert a small flat blade in the access slot
between the lamp base and lamp lens.
(3) Pry the lamp lens upward and remove the
lamp lens (Fig. 21).
(4) Depress the bulb terminal inward (Fig. 22) to
release the bulb.
INSTALLATION
(1) Engage the replacement bulb wire loop to the
terminal closest to the lamp base wire connector (Fig.
22).
(2) Depress the opposite terminal inward and
engage the remaining bulb wire loop.
(3) Position the lamp lens on the lamp base and
press into place (Fig. 21).
(4) Connect the battery negative cable.
UNDERHOOD LAMP UNIT
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
Fig. 19 TAIL LAMP UNIT
1 - SCREW
2 - ELECTRICAL CONNECTOR
3 - TAILLAMP UNIT
Fig. 20 Trailer Tow Wiring
1 - RETAINER CLIP (4)
2 - REAR BODY HARNESS (TRAILER TOW TAKE OUT)
3 - RETAINER CLIP (2)
4 - WIRE HARNESS CONNECTOR
8L - 22 LAMPS/LIGHTING - EXTERIORDR
TAIL LAMP UNIT (Continued)

TIRE REVOLUTIONS PER MILE,
SPECIFICATIONS.....................22-10
TIRE ROTATION - STANDARD
PROCEDURE.........................22-2
TIRE WEAR PATTERNS - DIAGNOSIS
AND TESTING........................22-8
TIRES - DESCRIPTION.................22-5
TIRES - DESCRIPTION, RADIAL - PLY.....22-6
TIRES - DESCRIPTION, REPLACEMENT....22-6
TIRE/VEHICLE LEAD - DIAGNOSIS AND
TESTING............................22-8
TO COOLER - INSTALLATION, RETURN
HOSE - GEAR..................19-43,19-44
TO COOLER - INSTALLATION, RETURN
HOSE - RESERVOIR.............19-43,19-44
TO COOLER - REMOVAL, RETURN HOSE
- GEAR............................19-43
TO COOLER - REMOVAL, RETURN HOSE
- RESERVOIR..................19-43,19-44
TO GROUND - STANDARD PROCEDURE,
TESTING FOR A SHORT.............8W-01-9
TO GROUND ON FUSES POWERING
SEVERAL LOADS - STANDARD
PROCEDURE, TESTING FOR A SHORT . 8W-01-10
TO OIL COOLER - INSTALLATION, AIR.....7-75
TO OIL COOLER - REMOVAL, AIR.........7-74
TO OIL COOLER - REMOVAL, WATER......7-74
TO USE WIRING DIAGRAMS -
DESCRIPTION, HOW................8W-01-1
TOE ADJUSTMENT - STANDARD
PROCEDURE..........................2-4
TOE ADJUSTMENT - STANDARD
PROCEDURE, CAMBER, CASTER..........2-4
TOOL - ADJUSTMENT, WITH ADJUSTING . . . 5-36
TOOLS - 4.7L ENGINE, SPECIAL.........9-102
TOOLS - 5.7L ENGINE, SPECIAL.........9-192
TOOLS - 5.9L DIESEL ENGINE, SPECIAL . . 9-294
TOOLS - 5.9L ENGINE, SPECIAL.........9-240
TOOLS - 8.0L ENGINE, SPECIAL.........9-367
TOOLS - 9 1/4 AA, SPECIAL.............2-29
TOOLS - BASE BRAKES, SPECIAL.........5-5
TOOLS - BATTERY SYSTEM SPECIAL
TOOLS, SPECIAL......................8F-7
TOOLS - BODY, SPECIAL...............23-14
TOOLS - COOLING, SPECIAL.............7-20
TOOLS - DIESEL FUEL SYSTEM,
SPECIAL...........................14-60
TOOLS - FRONT SUSPENSION, SPECIAL . . . 2-11
TOOLS - FUEL SYSTEM, SPECIAL........14-5
TOOLS - OVERHEAD CONSOLE, SPECIAL . . 8M-6
TOOLS - POWER DISTRIBUTION
SYSTEMS, SPECIAL................8W-97-2
TOOLS - POWER STEERING GEAR,
SPECIAL...........................19-22
TOOLS - RE TRANSMISSION, SPECIAL . . 21-189,
21-370
TOOLS - RFE TRANSMISSION, SPECIAL . . 21-535
TOOLS - STEERING LINKAGE, SPECIAL . . . 19-35
TOOLS - STEERING, SPECIAL............19-5
TOOLS - TRANSFER CASE NV271/NV273,
SPECIAL....................21-650,21-714
TOOLS - WHEEL ALIGNMENT, SPECIAL.....2-7
TOOLS - WIRING/TERMINAL, SPECIAL . 8W-01-10
TOOLS, DIAGNOSIS AND TESTING -
SPECIAL............................11-4
TOOLS, FRONT AXLE - 9 1/4 AA -
SPECIAL............................3-53
TOOLS, FRONT AXLE - C205F - SPECIAL . . . 3-30
TOOLS, HALF SHAFT - SPECIAL..........3-12
TOOLS, HEADLAMP ALIGNMENT -
SPECIAL............................8L-7
TOOLS, MANUAL TRANSMISSION -
NV3500 - SPECIAL...................21-40
TOOLS, MANUAL TRANSMISSION -
NV4500 - SPECIAL...................21-79
TOOLS, MANUAL TRANSMISSION -
NV5600 - SPECIAL..................21-122
TOOLS, PROPELLER SHAFT - SPECIAL.....3-6
TOOLS, REAR AXLE - 10 1/2 AA -
SPECIAL...........................3-108
TOOLS, REAR AXLE - 11 1/2 AA -
SPECIAL
...........................3-135
TOOLS, REAR AXLE - 9 1/4 - SPECIAL
.....3-80
TOOLS, SPECIAL TOOLS - BATTERY
SYSTEM SPECIAL
.....................8F-7
TOOLS, SPECIFICATIONS - SPECIAL
.......9-16
TOP COVER - INSTALLATION,
INSTRUMENT PANEL
..................23-60TOP COVER - REMOVAL, INSTRUMENT
PANEL.............................23-59
TORSION BAR - DESCRIPTION...........2-25
TORSION BAR - INSTALLATION..........2-26
TORSION BAR - OPERATION.............2-25
TORSION BAR - REMOVAL..............2-25
TORSION BAR CROSS MEMBER
BUSHING - INSTALLATION..............2-14
TORSION BAR CROSSMEMBER
BUSHING - REMOVAL..................2-12
TOUCH-UP - DESCRIPTION, PAINT.......23-75
TOUCH-UP - STANDARD PROCEDURE,
PAINT.............................23-75
TOW HOOK ASSEMBLY - INSTALLATION,
FRONT.............................13-26
TOW HOOK ASSEMBLY - REMOVAL,
FRONT.............................13-26
TOW WIRING - DESCRIPTION, TRAILER . . 8L-22
TOWING - STANDARD PROCEDURE.......0-15
TRACK - DESCRIPTION, POWER SEAT....8N-18
TRACK - DIAGNOSIS AND TESTING,
POWER SEAT.......................8N-18
TRACK - INSTALLATION, POWER SEAT . . . 8N-19
TRACK - INSTALLATION, SEAT..........23-83
TRACK - OPERATION, POWER SEAT.....8N-18
TRACK - REMOVAL, POWER SEAT.......8N-19
TRACK - REMOVAL, SEAT..............23-83
TRACK BAR - INSTALLATION...........19-37
TRACK BAR - REMOVAL................19-37
TRAC-RITE - ASSEMBLY, DIFFERENTIAL . . 3-120,
3-147
TRAC-RITE - CLEANING, DIFFERENTIAL . . 3-119,
3-146
TRAC-RITE - DESCRIPTION,
DIFFERENTIAL..................3-118,3-145
TRAC-RITE - DISASSEMBLY,
DIFFERENTIAL..................3-118,3-145
TRAC-RITE - INSPECTION, DIFFERENTIAL . 3-119,
3-146
TRAC-RITE - OPERATION, DIFFERENTIAL . 3-118,
3-145
TRAILER HITCH - INSTALLATION........13-25
TRAILER HITCH - REMOVAL............13-25
TRAILER TOW WIRING - DESCRIPTION . . . 8L-22
TRANS COOLER - 5.9L DIESEL -
DESCRIPTION........................7-73
TRANS COOLER - 5.9L DIESEL -
OPERATION..........................7-74
TRANS TEMP INDICATOR -
DESCRIPTION.......................8J-38
TRANS TEMP INDICATOR - OPERATION . . . 8J-38
TRANSDUCER - DESCRIPTION, A/C
PRESSURE.........................24-15
TRANSDUCER - DIAGNOSIS AND
TESTING, A/C PRESSURE..............24-15
TRANSDUCER - INSTALLATION, A/C
PRESSURE.........................24-16
TRANSDUCER - OPERATION, A/C
PRESSURE.........................24-15
TRANSDUCER - REMOVAL, A/C
PRESSURE.........................24-16
TRANSFER CASE - NV241 GENII -
ASSEMBLY.........................21-604
TRANSFER CASE - NV241 GENII -
CLEANING
.........................21-602
TRANSFER CASE - NV241 GENII -
DESCRIPTION
.........................0-4
TRANSFER CASE - NV241 GENII -
DESCRIPTION
......................21-591
TRANSFER CASE - NV241 GENII -
DIAGNOSIS AND TESTING
............21-592
TRANSFER CASE - NV241 GENII -
DISASSEMBLY
......................21-593
TRANSFER CASE - NV241 GENII -
INSPECTION
.......................21-602
TRANSFER CASE - NV241 GENII -
INSTALLATION
......................21-614
TRANSFER CASE - NV241 GENII -
OPERATION
........................21-591
TRANSFER CASE - NV241 GENII -
REMOVAL
.........................21-593
TRANSFER CASE - NV243 - ASSEMBLY
. . 21-670
TRANSFER CASE - NV243 - CLEANING
. . 21-668
TRANSFER CASE - NV243 -
DESCRIPTION
.........................0-4
TRANSFER CASE - NV243 -
DESCRIPTION
......................21-658TRANSFER CASE - NV243 - DIAGNOSIS
AND TESTING......................21-659
TRANSFER CASE - NV243 -
DISASSEMBLY......................21-660
TRANSFER CASE - NV243 - INSPECTION . 21-668
TRANSFER CASE - NV243 -
INSTALLATION......................21-679
TRANSFER CASE - NV243 - OPERATION . 21-659
TRANSFER CASE - NV243 - REMOVAL . . . 21-660
TRANSFER CASE - NV271 - ASSEMBLY . . 21-637
TRANSFER CASE - NV271 - CLEANING . . 21-635
TRANSFER CASE - NV271 -
DESCRIPTION.........................0-4
TRANSFER CASE - NV271 -
DESCRIPTION......................21-623
TRANSFER CASE - NV271 - DIAGNOSIS
AND TESTING......................21-624
TRANSFER CASE - NV271 -
DISASSEMBLY......................21-625
TRANSFER CASE - NV271 - INSPECTION . 21-635
TRANSFER CASE - NV271 -
INSTALLATION......................21-649
TRANSFER CASE - NV271 - OPERATION . 21-623
TRANSFER CASE - NV271 - REMOVAL . . . 21-625
TRANSFER CASE - NV273 - ASSEMBLY . . 21-701
TRANSFER CASE - NV273 - CLEANING . . 21-698
TRANSFER CASE - NV273 -
DESCRIPTION.........................0-4
TRANSFER CASE - NV273 -
DESCRIPTION......................21-687
TRANSFER CASE - NV273 - DIAGNOSIS
AND TESTING......................21-688
TRANSFER CASE - NV273 -
DISASSEMBLY......................21-689
TRANSFER CASE - NV273 - INSPECTION . 21-699
TRANSFER CASE - NV273 -
INSTALLATION......................21-713
TRANSFER CASE - NV273 - OPERATION . 21-688
TRANSFER CASE - NV273 - REMOVAL . . . 21-689
TRANSFER CASE CONTROL MODULE -
DESCRIPTION.......................8E-15
TRANSFER CASE CONTROL MODULE -
OPERATION.........................8E-15
TRANSFER CASE, NV241 GENII........21-614
TRANSFER CASE, NV241/NV243 . . 21-615,21-680
TRANSFER CASE, NV243.............21-680
TRANSFER CASE, NV271.............21-649
TRANSFER CASE NV271/NV273, SPECIAL
TOOLS......................21-650,21-714
TRANSFER CASE, NV273.............21-713
TRANSFER CASE SKID PLATE -
INSTALLATION.......................13-26
TRANSFER CASE SKID PLATE -
REMOVAL..........................13-26
TRANSFER PUMP - DESCRIPTION, FUEL . . 14-75
TRANSFER PUMP - INSTALLATION, FUEL . 14-76
TRANSFER PUMP - OPERATION, FUEL....14-76
TRANSFER PUMP - REMOVAL, FUEL.....14-76
TRANSMISSION - 45RFE/545RFE -
DESCRIPTION, AUTOMATIC............21-489
TRANSMISSION - 45RFE/545RFE -
OPERATION, AUTOMATIC.............21-490
TRANSMISSION - 46RE - DESCRIPTION,
AUTOMATIC
........................21-131
TRANSMISSION - 46RE - OPERATION,
AUTOMATIC
........................21-133
TRANSMISSION - 48RE - DESCRIPTION,
AUTOMATIC
........................21-312
TRANSMISSION - 48RE - OPERATION,
AUTOMATIC
........................21-314
TRANSMISSION - CLEANING
..........21-104
TRANSMISSION - DESCRIPTION,
MANUAL
.............................0-4
TRANSMISSION - DIAGNOSIS AND
TESTING, AUTOMATIC
....21-139,21-320,21-491
TRANSMISSION - NV3500 - ASSEMBLY,
MANUAL
...........................21-17
TRANSMISSION - NV3500 - CLEANING,
MANUAL
...........................21-15
TRANSMISSION - NV3500 -
DESCRIPTION, MANUAL
................21-1
TRANSMISSION - NV3500 - DIAGNOSIS
AND TESTING, MANUAL
................21-3
TRANSMISSION - NV3500 -
DISASSEMBLY, MANUAL
................21-4
TRANSMISSION - NV3500 -
INSPECTION, MANUAL
................21-15
DRINDEX 35
Description Group-Page Description Group-Page Description Group-Page