length DODGE RAM 2001 Service User Guide

REMOVAL
Drive belts are equipped with a spring loaded auto-
matic belt tensioner (Fig. 16). This belt tensioner will
be used on all belt configurations, such as with or
without power steering or air conditioning. For more
information, refer to Automatic Belt Tensioner, pro-
ceeding in this group.
(1) Attach a socket/wrench to pulley mounting bolt
of automatic tensioner (Fig. 16). The threads on the
pulley mounting bolt are left- hand.
(2) Relax the tension from the belt by rotating the
tensioner counterclockwise (as viewed from front)
(Fig. 16). When all belt tension has been relaxed,
remove belt from tensioner pulley first and other pul-
leys last.
INSTALLATION
CAUTION: When installing the accessory drive belt,
the belt must be routed correctly. If not, engine may
overheat due to water pump rotating in wrong
direction. Refer to (Fig. 17) (Fig. 18) for correct
engine belt routing. The correct belt with correct
length must be used.
CAUTION: If the pulley is to be removed from the
tensioner, its mounting bolt has left-hand threads.
(1) Position drive belt over all pulleysexceptten-
sioner pulley.
(2) Attach a socket/wrench to pulley mounting bolt
of automatic tensioner (Fig. 16).
(3) Rotate socket/wrench counterclockwise. Install
belt over tensioner pulley. Let tensioner rotate back
into place. Remove wrench. Be sure belt is properly
seated on all pulleys.
Fig. 16 Belt Tensioner
1 - PULLEY BOLT
2 - IDLER PULLEY
3 - TENSIONER PULLEY
4 - TENSIONER
5 - TENSIONER MOUNTING BOLT
Fig. 17 Belt RoutingÐWith A/C
1 - AUTOMATIC TENSIONER
2 - GENERATOR PULLEY
3 - IDLER PULLEY
4 - A/C COMPRESSOR PUMP PULLEY
5 - POWER STEERING PUMP PULLEY
6 - WATER PUMP AND FAN PULLEY
7 - CRANKSHAFT PULLEY
8 - AIR PUMP (A.I.R.) PULLEY
7 - 30 ACCESSORY DRIVEBR/BE
DRIVE BELTS - 8.0L (Continued)

INSTALLATION
CAUTION: When installing the accessory drive belt,
the belt must be routed correctly. If not, engine may
overheat due to water pump rotating in wrong
direction. Refer to (Fig. 21) (Fig. 22) for correct
engine belt routing. The correct belt with correct
length must be used.
(1) Position drive belt over all pulleysexcept
water pump pulley.
(2) Attach a 3/8 inch ratchet to tensioner.
(3) Rotate ratchet and belt tensioner counterclock-
wise. Place belt over water pump pulley. Let ten-
sioner rotate back into place. Remove ratchet. Be
sure belt is properly seated on all pulleys.
VACUUM PUMP - 5.9L DIESEL
DESCRIPTION
The vacuum pump and the power steering pump
are combined into a single assembly on diesel engine
models (Fig. 23). Both pumps are operated by a drive
gear attached to the vacuum pump shaft. The shaft
gear is driven by the camshaft gear.
The vacuum pump is a constant displacement,
vane-type pump. Vacuum is generated by four vanes
mounted in the pump rotor. The rotor is located in
the pump housing and is pressed onto the pump
shaft.
The vacuum and steering pumps are operated by a
single drive gear pressed onto the vacuum pump
shaft. The drive gear is operated by the engine cam-
shaft gear.
The vacuum and power steering pump shafts are
connected by a coupling. Each pump shaft has an
adapter with drive lugs that engage in the coupling.
The vacuum pump rotating components are lubri-
cated by engine oil. Lubricating oil is supplied to the
pump through an oil line at the underside of the
pump housing.
Fig. 21 Belt RoutingÐ5.9L Diesel EngineÐWith A/C
1 - GENERATOR PULLEY
2 - WATER PUMP PULLEY
3 - FAN PULLEY
4 - CRANKSHAFT PULLEY
5 - AUTOMATIC TENSIONER
6 - A/C COMPRESSOR PUMP PULLEY
Fig. 22 Belt RoutingÐ5.9L Diesel EngineÐWithout
A/C
1 - GENERATOR PULLEY
2 - FAN PULLEY
3 - CRANKSHAFT PULLEY
4 - AUTOMATIC TENSIONER
5 - WATER PUMP PULLEY
7 - 34 ACCESSORY DRIVEBR/BE
DRIVE BELTS - 5.9L DIESEL (Continued)

(4) Position thermostat housing to intake manifold.
Note the word FRONT stamped on housing (Fig. 20).
For adequate clearance, thismustbe placed towards
front of vehicle. The housing is slightly angled for-
ward after installation to intake manifold.
(5) Install two housing-to-intake manifold bolts.
Tighten bolts to 23 N´m (200 in. lbs.) torque.
(6) Install radiator upper hose to thermostat hous-
ing.
CAUTION: When installing the serpentine accessory
drive belt, the belt must be routed correctly. If not,
engine may overheat due to water pump rotating in
wrong direction. Refer to (Fig. 21) for correct 3.9L,
5.2L and 5.9L engine belt routing. The correct belt
with correct length must be used.
(7) Air Conditioned vehicles; Install generator.
Tighten bolts to 41 N´m (30 ft. lbs.).
(8) Install support bracket (generator mounting
bracket-to-intake manifold) (Fig. 16). Tighten bolts to
54 N´m (40 ft. lbs.) torque.
(9) Install accessory drive belt (Fig. 17)(Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION).
(10) Fill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(11) Connect battery negative cable.(12) Start and warm the engine. Check for leaks.
Fig. 19 ThermostatÐ3.9L and 5.9L Engines
1 - THERMOSTAT HOUSING
2 - GASKET
3 - INTAKE MANIFOLD
4 - THERMOSTAT
5 - MACHINED GROOVEFig. 20 Thermostat PositionÐ5.2L and 5.9L Engines
Fig. 21 Belt RoutingÐ5.2L and 5.9L Engines
1 - IDLER PULLEY
2 - GENERATOR PULLEY
3 - A/C COMPRESSOR PULLEY
4 - IF W/OUT A/C
5 - POWER STEERING PUMP PULLEY
6 - WATER PUMP PULLEY
7 - CRANKSHAFT PULLEY
8 - AUTOMATIC TENSIONER
BR/BEENGINE 7 - 51
ENGINE COOLANT THERMOSTAT - 3.9L/5.2L/5.9L (Continued)

CAUTION: When installing the serpentine accessory
drive belt, the belt must be routed correctly. If not,
the engine may overheat due to the water pump
rotating in the wrong direction (Refer to 7 - COOL-
ING/ACCESSORY DRIVE/DRIVE BELTS - INSTALLA-
TION). The correct belt with the correct length must
be used.(12) Install air cleaner assembly.
(13) Install upper radiator hose to radiator.
(14) Connect throttle cable to clip at radiator fan
shroud.
(15) Connect wiring harness to A/C compressor.
(16) Fill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(17) Start and warm the engine. Check for leaks.
INSTALLATIONÐWATER PUMP BYPASS HOSE
WITHOUT AIR CONDITIONING
(1) Position bypass hose clamps to the center of
hose.
(2) Install bypass hose to engine.
(3) Secure both hose clamps.
(4) Fill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(5) Start and warm the engine. Check for leaks.
Fig. 72 Tensioner Mounting
1 - DOWEL PIN HOLE
2 - TENSIONER MOUNTING BRACKET
7 - 78 ENGINEBR/BE
WATER PUMP INLET TUBE - 3.9L/5.2L/5.9L (Continued)

commercial radio stations in both the Amplitude
Modulating (AM) and Frequency Modulating (FM)
frequency ranges. These electromagnetic radio fre-
quency signals induce small electrical modulations
into the antenna as they move past the mast. The
antenna body transfers the weak electromagnetic
radio waves induced into the rigid antenna mast into
the center conductor of the flexible primary antenna
coaxial cable. The braided outer shield of the
antenna coaxial cable is grounded through both the
antenna body and the radio chassis, effectively
shielding the radio waves as they are conducted to
the radio. The radio then tunes and amplifies the
weak radio signals into stronger electrical signals in
order to operate the audio system speakers.
The antenna body includes an integral flange that
mates with and grounds the antenna body to the
underside of the fender panel sheet metal. Above the
fender panel, the antenna body has a short nipple
that is externally threaded to accept the antenna cap
nut. Inside the nipple is a plastic insulator tube, and
inside this insulator is an internally threaded metal
receptacle that accepts the adapter stud on the bot-
tom of the antenna mast. The antenna adapter
serves as an above fender interface to mount and
secure the antenna body to the vehicle. The antenna
adapter is a black molded plastic component that
provides a functional transition between the top of
the fender and the antenna cap nut, while concealing
the edges of the antenna mounting hole and protect-
ing the painted finish of the fender from marring as
the antenna cap nut is tightened. The adapter is
installed over and shrouds the threaded nipple of the
antenna body, which is installed from under and pro-
trudes through the top of the mounting hole in the
fender. The antenna cap nut is installed on top of the
antenna adapter and tightened onto the external
threads of the antenna body nipple to effectively
secure and ground the antenna body to the fender.
Three notches on the outer circumference of the cap
nut are engaged by matching projections of an
antenna nut wrench (Special Tool C-4816) to facili-
tate the removal and installation of this special fas-
tener. Proper tightening of the antenna cap nut is
critical to ensuring proper grounding of the antenna
body to the fender sheet metal, which is necessary
for clear radio signal reception.
A short length of coaxial cable serves as the pri-
mary antenna cable. The center conductor of the
cable is connected to the antenna mast receptacle.
The outer wire mesh of the cable is connected to and
grounded through the antenna body. One end of the
primary antenna cable is securely crimped to the
lower end of the antenna body, while the opposite
end features a simple push/pull-type male coaxial
cable connector that serves as the in-line connector tothe instrument panel (secondary) antenna coaxial
cable. The primary coaxial cable includes a grommet
that seals the cable to an entry hole in the right cowl
side outer panel where the cable passes into the pas-
senger compartment of the vehicle. The secondary
antenna cable has a push/pull-type male coaxial
cable connector on the radio end, and a push/pull-
type female coaxial cable connector on the opposite
end, which serves as the in-line connector to the pri-
mary antenna cable. In the passenger compartment
the primary cable is routed to the lower right side of
the instrument panel, where it is connected to the
secondary instrument panel antenna cable. The
instrument panel antenna cable is routed near the
instrument panel wire harness through the instru-
ment panel to the radio and is secured to the instru-
ment panel structural support with small metal
push-on retainers. This two-piece antenna cable
arrangement allows the instrument panel or the
antenna body and cable to be removed or installed
without disturbing the radio.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ANTENNA
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO ELECTRICAL, RESTRAINTS
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. FAILURE
TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
The following four tests are used to diagnose the
antenna with an ohmmeter:
²Test 1- Mast to ground test
²Test 2- Tip-of-mast to tip-of-conductor test
²Test 3- Body ground to battery ground test
²Test 4- Body ground to coaxial shield test.
The ohmmeter test lead connections for each test
are shown in Antenna Tests (Fig. 1).
NOTE: This model has a two-piece antenna coaxial
cable. Tests 2 and 4 must be conducted in two
steps to isolate a coaxial cable problem; from the
coaxial cable connection under the right end of the
instrument panel near the right cowl side inner
panel to the antenna base, and then from the coax-
ial cable connection to the radio receiver chassis
connection.
BR/BEAUDIO 8A - 5
ANTENNA BODY & CABLE (Continued)

(3) Remove the foam tape to access the coaxial
cable connector. Disconnect the connector by pulling
it apart while twisting the metal connector halves.
Do not pull on the cable.
(4) Securely tie a suitable length of cord or twine
to the antenna half of the coaxial cable connector.
This cord will be used to pull or ªfishº the cable back
into position during installation.
(5) Reach above the Powertrain Control Module
(PCM) on the right side of the dash panel in the
engine compartment to disengage the antenna coax-
ial cable grommet from the hole in the dash panel
(Fig. 3).
(6) Pull the antenna coaxial cable out of the pas-
senger compartment and into the engine compart-
ment through the hole in the dash panel.
(7) Raise the sleeve on the antenna mast far
enough to access and unscrew the antenna mast from
the antenna body (Fig. 4).
(8) Remove the antenna cap nut using an antenna
nut wrench (Special Tool C-4816) (Fig. 5).
(9) Remove the antenna adapter from the top of
the fender.
(10) Lower the antenna body and cable assembly
through the top of the fender.(11) Pull the antenna body and cable out through
the opening between the right cowl side outer panel
and the top of the fender, while feeding the antenna
coaxial cable out of the engine compartment through
the hole in the right cowl side reinforcement.
(12) Untie the cord or twine from the antenna
body and cable coaxial cable connector, leaving the
cord or twine in the place of the cable through the
vehicle.
(13) Remove the antenna body and cable from the
vehicle.
INSTALLATION
(1) Tie the end of the cord or twine that was used
during instrument panel antenna cable removal
Fig. 3 Antenna Mounting
1 - COWL SIDE REINFORCEMENT
2 - DASH PANEL
3 - GROMMET
4 - ANTENNA BODY AND CABLE
5 - ADAPTER
6 - MAST
7 - SLEEVE
8 - NUT
Fig. 4 Antenna Mast Remove/Install - Typical
1 - ANTENNA MAST
2 - CAP NUT
3 - ADAPTER
Fig. 5 Antenna Cap Nut Remove/Install - Typical
1 - CAP NUT
2 - ANTENNA ADAPTER
3 - TOOL
BR/BEAUDIO 8A - 7
ANTENNA BODY & CABLE (Continued)

There should now be battery voltage. If OK, repair
the open amplified speaker (+) circuits to the speak-
er-mounted amplifiers as required. If not OK, replace
the faulty filter, choke and speaker relay unit.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Reach under the driver side of the instrument
panel near the 16-way data link connector and
inboard of the ash receiver to access the filter, choke,
and speaker relay (Fig. 6) .
(3) Disconnect the instrument panel wire harness
connector from the filter, choke and speaker relay
wire harness connector.
(4) Remove the two screws that secure the filter,
choke, and speaker relay mounting bracket to the
instrument panel center brace.
(5) Remove the filter, choke, and speaker relay
unit from under the instrument panel.
INSTALLATION
(1) Position the filter, choke, and speaker relay
unit under the instrument panel.(2) Install and tighten the two screws that secure
the filter, choke, and speaker relay mounting bracket
to the instrument panel center brace. Tighten the
screws to 2.7 N´m (24 in. lbs.).
(3) Reconnect the instrument panel wire harness
connector to the filter, choke and speaker relay wire
harness connector.
(4) Reconnect the battery negative cable.
INSTRUMENT PANEL
ANTENNA CABLE
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Reach under the passenger side of the instru-
ment panel near the right cowl side inner panel to
disengage the coaxial cable connector from the
retainer clip located on the bottom of the heater-A/C
housing .
(3) Remove the foam tape to access the coaxial
cable connector. Disconnect the connector by pulling
it apart while twisting the metal connector halves.
Do not pull on the cable.
(4) Securely tie a suitable length of cord or twine
to the instrument panel half of the antenna coaxial
cable connector. This cord will be used to pull or
ªfishº the cable back into position during installation.
(5) Roll down the glove box from the instrument
panel. Refer to Body, Instrument Panel for the proce-
dures.
(6) Reach through the glove box opening to disen-
gage the antenna cable from the retainer clips on the
back of the instrument panel (Fig. 7).
Fig. 6 Filter, Choke, and Speaker Relay Remove/
Install
1 - ASH RECEIVER HOUSING
2 - DATA LINK CONNECTOR
3 - CENTER BRACE
4 - SCREW
5 - CHOKE AND RELAY
6 - WIRE HARNESS CONNECTORS
Fig. 7 ANTENNA CABLE ROUTING
1 - RETAINER CLIPS
2 - TO RADIO
3 - TO ANTENNA
BR/BEAUDIO 8A - 9
RADIO CHOKE RELAY (Continued)

Once a message is broadcast over the CCD data
bus, all electronic control modules on the data bus
have the ability to receive it through their CCD chip.
Reception of CCD messages is also carried out by the
transceiver in the CCD chip. The transceiver moni-
tors the voltage on the data bus for any fluctuations.
When data bus voltage fluctuations are detected,
they are interpreted by the transceiver as binary
messages and sent to the electronic control module's
microprocessor.
BUS BIAS AND TERMINATION
The voltage network used by the CCD data bus to
transmit messages requires both bias and termina-
tion. At least one electronic control module on the
data bus must provide a voltage source for the CCD
data bus network known as bus bias, and there must
be at least one bus termination point for the data bus
circuit to be complete. However, while bias and ter-
mination are both required for data bus operation,
they both do not have to be within the same elec-
tronic control module. The CCD data bus is biased to
approximately 2.5 volts. With each of the electronic
control modules wired in parallel to the data bus, all
modules utilize the same bus bias. Therefore, based
upon vehicle options, the data bus can accommodate
two or twenty electronic control modules without
affecting bus voltage.
The power supplied to the data bus is known as
bus biasing. Bus bias is provided through a series cir-
cuit. To properly bias the data bus circuits, a 5 volt
supply is provided through a 13 kilohm resistor to
the Bus (±) circuit (Fig. 6). Voltage from the Bus (±)
circuit flows through a 120 ohm termination resistor
to the Bus (+) circuit. The Bus (+) circuit is grounded
through another 13 kilohm resistor. While at least
one termination resistor is required for the system to
operate, most Chrysler systems use two. The second
termination resistor serves as a backup (Fig. 7). The
termination resistor provides a path for the bus bias
voltage. Without a termination point, voltage biasing
would not occur. Voltage would go to 5 volts on one
bus wire and 0 volts on the other bus wire.
The voltage drop through the termination resistor
creates 2.51 volts on Bus (±), and 2.49 volts on Bus
(+). The voltage difference between the two circuits is
0.02 volts. When the data bus voltage differential is a
steady 0.02 volts, the CCD system is considered
ªidle.º When no input is received from any module
and the ignition switch is in the Off position for a
pre-programmed length of time, the bus data
becomes inactive or enters the ºsleep mode.º Elec-
tronic control modules that provide bus bias can be
programmed to ºwake upº the data bus and becomeactive upon receiving any predetermined input or
when the ignition switch is turned to the On posi-
tion.
BUS MESSAGING
The electronic control modules used in the CCD
data bus system contain microprocessors. Digital sig-
nals are the means by which microprocessors operate
internally and communicate messages to other micro-
processors. Digital signals are limited to two states,
voltage high or voltage low, corresponding to either a
one or a zero. Unlike conventional binary code, the
CCD data bus systems translate a small voltage dif-
ference as a one (1), and a larger voltage difference
as a zero (0). The use of the 0 and 1 is referred to as
binary coding. Each binary number is called a bit,
and eight bits make up a byte. For example:
01011101 represents a message. The controllers in
the multiplex system are able to send thousands of
these bytes strung together to communicate a variety
of messages. Through the use of binary data trans-
mission, all electronic control modules on the data
bus can communicate with each other.
The microprocessors in the CCD data bus system
translate the binary messages into Hexadecimal
Code (or Hex Code). Hex code is the means by which
microprocessors communicate and interpret mes-
sages. When fault codes are received by the DRBIIIt
scan tool, they are translated into text for display on
the DRBIIItscreen. Although not displayed by the
DRBIIItfor Body Systems, hex codes are shown by
the DRBIIItfor Engine System faults.
Fig. 6 Bus Biasing
8E - 8 ELECTRONIC CONTROL MODULESBR/BE
COMMUNICATION (Continued)

When the microprocessor signals the transceiver in
the CCD chip to broadcast a message, the transceiver
turns the current drivers On and Off, which cycles
the voltage on the CCD data bus circuits to corre-
spond to the message. At idle, the CCD system rec-
ognizes the 0.02 voltage differential as a binary bit 1.
When the current drivers are actuated, the voltage
differential from idle must increase by 0.02 volt for
the CCD system to recognize a binary bit 0 (Fig. 8).
The nominal voltage differential for a 0 bit is 0.100
volts. However, data bus voltage differentials can
range anywhere between 0.02 and 0.120 volt.
BUS MESSAGE CODING
The first part of a data bus message has an Iden-
tification (ID) byte. The ID byte contains message
priority, message identification, message content and
message length information. All messages sent over
the data bus are coded for both priority and identifi-
cation.PRIORITY
Messages can be broadcast almost simultaneously
by modules over the CCD data bus. Therefore, all
messages are defined and ranked by a predetermined
priority. When two CCD chips start a message at
exactly the same time, non-destructive arbitration
occurs between the two CCD chips. Arbitration will
occur based upon the priority code, to determine
which message takes priority on the data bus and to
prevent data collision. If a CCD chip senses a mes-
sage of higher priority being transmitted, it stops
transmitting its message. The higher priority mes-
sage is then transmitted in its entirety without inter-
ruption. The other CCD chips on the data bus do not
allow any other messages to be broadcast.
To determine the winner in an arbitration, all mes-
sages start with an ID byte which contains the pre-
determined priority code. In the digital broadcast,
zero is the dominant bit. All ID bytes start with a
zero. This is the start of the message. With zeros
being the dominant bit, messages starting with more
Fig. 7 Bus Termination
BR/BEELECTRONIC CONTROL MODULES 8E - 9
COMMUNICATION (Continued)

zeros have a higher priority. For example: of the two
messages below, Message #2 loses arbitration at the
second bit, where Message #1 has a zero and Mes-
sage #2 has a one (Fig. 9). After the message is
broadcast, an idle period occurs while all micropro-
cessors can queue, if necessary, and attempt to
broadcast their messages again.
²Message #1 = 00010110
²Message #2 = 01010101MESSAGE IDENTIFICATION
Because messages are broadcast over the data bus,
all modules can receive them, yet not all modules
need all messages. In order to enhance microproces-
sor speed, unneeded messages are filtered out. The
ID byte, along with showing message priority, also
identifies the data, content and length. The electronic
control module, through its CCD chip transceiver,
monitors the ID code of the messages. If the message
is not for that particular module, the message is sim-
ply ignored. Once the module recognizes a message
that it requires, the rest of the message is monitored
and processed.
TRANSMISSION VERIFICATION
Once a CCD chip transmits a message over the
CCD data bus, the message is received by the trans-
mitting module at the same time through the CCD
chip differential transceiver. The module knows the
message was broadcast correctly when it receives its
own message back. If the message received does not
match the message transmitted, the message is said
to be corrupt.
Corruption occurs when the message is incorrectly
transmitted on the data bus. Corruption can also
occur from interference, wiring problems, or other
data bus problems. In the case of a corrupt message,
Fig. 8 Voltage Cycling to Correspond to Message
Fig. 9 Message Arbitration
8E - 10 ELECTRONIC CONTROL MODULESBR/BE
COMMUNICATION (Continued)