2003 DODGE RAM engine

DESCRIPTION N´m Ft. Lbs. In. Lbs.
Generator Lower Pivot Bolt / Nut -
5.9L Gas Engine41 30 -
Generator Vertical Mounting Bolt -
3.7L / 4.7L Engines55 40 -
Generator (long) Horizontal
Mounting Bolt - 3.7L / 4.7L Engines55 40 -
Generator (short) Horizontal
Mounting Bolt - 3.7L / 4.7L Engines74 55 -
Generator B+ Output Cable
Terminal Nut12 - 108
BATTERY TEMPERATURE
SENSOR
DESCRIPTION
The Battery Temperature Sensor (BTS) is attached
to the battery tray located under the battery.
OPERATION
The BTS is used to determine the battery temper-
ature and control battery charging rate. This temper-
ature data, along with data from monitored line
voltage, is used by the PCM (ECM Diesel) to vary the
battery charging rate. System voltage will be higher
at colder temperatures and is gradually reduced at
warmer temperatures.
The PCM sends 5 volts to the sensor and is
grounded through the sensor return line. As temper-
ature increases, resistance in the sensor decreases
and the detection voltage at the PCM increases.
The BTS is also used for OBD II diagnostics. Cer-
tain faults and OBD II monitors are either enabled
or disabled, depending upon BTS input (for example,
disable purge and enable Leak Detection Pump
(LDP) and O2 sensor heater tests). Most OBD II
monitors are disabled below 20ÉF.
REMOVAL
The battery temperature sensor is located under
the vehicle battery and is attached (snapped into) a
mounting hole on battery tray (Fig. 1).
(1) Remove battery. Refer to 8, Battery for proce-
dures.
(2) Pry sensor straight up from battery tray
mounting hole to gain access to electrical connector
(Fig. 1).
(3) Disconnect sensor from engine wire harness
electrical connector.INSTALLATION
The battery temperature sensor is located under
the vehicle battery and is attached (snapped into) a
mounting hole on battery tray.
(1) Pull electrical connector up through mounting
hole in top of battery tray.
(2) Connect sensor.
(3) Snap sensor into battery tray.
(4) Install battery. Refer to 8, Battery for proce-
dures.
Fig. 1 BATTERY TEMPERATURE SENSOR
LOCATION
1 - BATTERY TEMP. SENSOR
2 - BATTERY
3 - SENSOR ELEC. CONNECT.
4 - BATTERY TRAY
DRCHARGING 8F - 21
CHARGING (Continued)

GENERATOR
DESCRIPTION
The generator is belt-driven by the engine using a
serpentine type drive belt. It is serviced only as a
complete assembly. If the generator fails for any rea-
son, the entire assembly must be replaced.
OPERATION
As the energized rotor begins to rotate within the
generator, the spinning magnetic field induces a cur-
rent into the windings of the stator coil. Once the
generator begins producing sufficient current, it also
provides the current needed to energize the rotor.
The stator winding connections deliver the induced
alternating current to 3 positive and 3 negative
diodes for rectification. From the diodes, rectified
direct current is delivered to the vehicle electrical
system through the generator battery terminal.
Although the generators appear the same exter-
nally, different generators with different output rat-
ings are used on this vehicle. Be certain that the
replacement generator has the same output rating
and part number as the original unit. Refer to Gen-
erator Ratings in the Specifications section at the
back of this group for amperage ratings and part
numbers.
Noise emitting from the generator may be caused
by: worn, loose or defective bearings; a loose or defec-
tive drive pulley; incorrect, worn, damaged or misad-
justed fan drive belt; loose mounting bolts; a
misaligned drive pulley or a defective stator or diode.
REMOVAL
3.7L / 4.7L
WARNING: DISCONNECT NEGATIVE CABLE FROM
BATTERY BEFORE REMOVING BATTERY OUTPUT
WIRE (B+ WIRE) FROM GENERATOR. FAILURE TO
DO SO CAN RESULT IN INJURY OR DAMAGE TO
ELECTRICAL SYSTEM.
(1) Disconnect negative battery cable at battery.
(2) Remove generator drive belt. Refer to 7, Cool-
ing System for procedure.
(3) Unsnap plastic insulator cap from B+ output
terminal (Fig. 2).
(4) Remove B+ terminal mounting nut at rear of
generator (Fig. 2). Disconnect terminal from genera-
tor.
(5) Disconnect field wire connector at rear of gen-
erator (Fig. 2) by pushing on connector tab.
(6) Remove 1 rear vertical generator mounting bolt
(Fig. 3).(7) Remove 2 front horizontal generator mounting
bolts (Fig. 3).
(8) Remove generator from vehicle.
Fig. 2 GENERATOR CONNECTORS - 3.7L / 4.7L
1 - GENERATOR
2-B+NUT
3 - PLASTIC INSULATOR CAP
4 - FIELD WIRE CONNECTOR
Fig. 3 REMOVE / INSTALL GENERATOR - 3.7L / 4.7L
1 - LOWER BOLTS
2 - REAR BOLT
3 - GENERATOR
8F - 22 CHARGINGDR

(8) Remove generator from vehicle.
INSTALLATION
3.7L / 4.7L
(1) Position generator to engine and install 2 hor-
izontal bolts and 1 vertical bolt.
(2) Tighten all 3 bolts. Refer to Torque Specifica-
tions.
(3) Snap field wire connector into rear of genera-
tor.
(4) Install B+ terminal eyelet to generator output
stud. Tighten mounting nut. Refer to Torque Specifi-
cations.
CAUTION: Never force a belt over a pulley rim
using a screwdriver. The synthetic fiber of the belt
can be damaged.
CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. The
water pump may be rotating in the wrong direction
if the belt is installed incorrectly, causing the
engine to overheat. Refer to belt routing label in
engine compartment, or refer to Belt Schematics in
7, Cooling System.
(5) Install generator drive belt. Refer to 7, Cooling
System for procedure.
(6) Install negative battery cable to battery.
5.7L
(1) Position generator to engine and install 2
mounting bolts.
(2) Tighten bolts. Refer to Torque Specifications.
(3) Position support bracket to front of generator
and install bolt and nuts. Tighten bolt / nuts. Refer
to Torque Specifications.
(4) Snap field wire connector into rear of genera-
tor.
(5) Install B+ terminal eyelet to generator output
stud. Tighten mounting nut. Refer to Torque Specifi-
cations.
CAUTION: Never force a belt over a pulley rim
using a screwdriver. The synthetic fiber of the belt
can be damaged.
CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. The
water pump may be rotating in the wrong direction
if the belt is installed incorrectly, causing the
engine to overheat. Refer to belt routing label in
engine compartment, or refer to Belt Schematics in
7, Cooling System.
(6) Install generator drive belt. Refer to 7, Cooling
System for procedure.
Fig. 9 REMOVE / INSTALL GENERATOR - 5.9L GAS
1 - MOUNTING BOLT
2 - GENERATOR
3 - MOUNTING BRACKET
4 - MOUNTING BOLT/NUT
Fig. 10 REMOVE / INSTALL GENERATOR ± 8.0L
ENGINE
1 - MOUNTING BOLT
2 - GENERATOR
3 - NUT
4 - MOUNTING BRACKET
5 - MOUNTING BOLT
DRCHARGING 8F - 25
GENERATOR (Continued)

(7) Install negative battery cable to battery.
5.9L Diesel
(1) Position generator to upper and lower mount-
ing brackets and install upper bolt and lower bolt /
nut.
(2) Tighten all bolts / nut. Refer to Torque Specifi-
cations.
(3) Snap field wire connector into rear of genera-
tor.
(4) Install B+ terminal eyelet to generator output
stud. Tighten mounting nut. Refer to Torque Specifi-
cations.
CAUTION: Never force a belt over a pulley rim
using a screwdriver. The synthetic fiber of the belt
can be damaged.
CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. The
water pump may be rotating in the wrong direction
if the belt is installed incorrectly, causing the
engine to overheat. Refer to belt routing label in
engine compartment, or refer to Belt Schematics in
7, Cooling System.
(5) Install generator drive belt. Refer to 7, Cooling
System for procedure.
(6) Install both negative battery cables to both bat-
teries.
8.0L
(1) Position generator to engine and install lower
bolt and upper bolt / nut.
(2) Tighten all bolts / nut. Refer to Torque Specifi-
cations.
(3) Snap field wire connector into rear of genera-
tor.
(4) Install B+ terminal eyelet to generator output
stud. Tighten mounting nut. Refer to Torque Specifi-
cations.
CAUTION: Never force a belt over a pulley rim
using a screwdriver. The synthetic fiber of the belt
can be damaged.CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. The
water pump may be rotating in the wrong direction
if the belt is installed incorrectly, causing the
engine to overheat. Refer to belt routing label in
engine compartment, or refer to Belt Schematics in
7, Cooling System.
(5) Install generator drive belt. Refer to 7, Cooling
System for procedure.
(6) Install negative battery cable to battery.
5.9L Gas
(1) Position generator to engine and install upper
bolt and lower bolt / nut.
(2) Tighten all bolts / nut. Refer to Torque Specifi-
cations.
(3) Snap field wire connector into rear of genera-
tor.
(4) Install B+ terminal eyelet to generator output
stud. Tighten mounting nut. Refer to Torque Specifi-
cations.
CAUTION: Never force a belt over a pulley rim
using a screwdriver. The synthetic fiber of the belt
can be damaged.
CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. The
water pump may be rotating in the wrong direction
if the belt is installed incorrectly, causing the
engine to overheat. Refer to belt routing label in
engine compartment, or refer to Belt Schematics in
7, Cooling System.
(5) Install generator drive belt. Refer to 7, Cooling
System for procedure.
(6) Install negative battery cable to battery.
8F - 26 CHARGINGDR
GENERATOR (Continued)

VOLTAGE REGULATOR
DESCRIPTION
The Electronic Voltage Regulator (EVR) is not a
separate component. It is actually a voltage regulat-
ing circuit located within the PCM (Powertrain Con-
trol Module) (within the ECM for diesel engines). The
EVR is not serviced separately. If replacement is nec-
essary, the PCM must be replaced.
OPERATION
The amount of direct current produced by the gen-
erator is controlled by EVR circuitry contained
within the PCM. This circuitry is connected in series
with the generators second rotor field terminal and
its ground.
Voltage is regulated by cycling the ground path to
control the strength of the rotor magnetic field. TheEVR circuitry monitors system line voltage (B+) and
battery temperature (refer to Battery Temperature
Sensor for more information). It then determines a
target charging voltage. If sensed battery voltage is
0.5 volts or lower than the target voltage, the PCM
grounds the field winding until sensed battery volt-
age is 0.5 volts above target voltage. A circuit in the
PCM cycles the ground side of the generator field up
to 100 times per second (100Hz), but has the capabil-
ity to ground the field control wire 100% of the time
(full field) to achieve the target voltage. If the charg-
ing rate cannot be monitored (limp-in), a duty cycle
of 25% is used by the PCM in order to have some
generator output. Also refer to Charging System
Operation for additional information.
DRCHARGING 8F - 27

STARTING
TABLE OF CONTENTS
page page
STARTING
DESCRIPTION.........................28
OPERATION...........................28
DIAGNOSIS AND TESTING - STARTING
SYSTEM............................29
SPECIFICATIONS
STARTING SYSTEM...................33
SPECIFICATIONS - TORQUE - STARTING
SYSTEM............................34
STARTER MOTOR
DIAGNOSIS AND TESTING - STARTER
MOTOR .............................34REMOVAL.............................34
INSTALLATION.........................37
STARTER MOTOR RELAY
DESCRIPTION.........................38
OPERATION...........................38
DIAGNOSIS AND TESTING - STARTER RELAY . 38
REMOVAL.............................39
INSTALLATION.........................39
STARTING
DESCRIPTION
The starting system consists of:
²Starter relay
²Starter motor (including an integral starter sole-
noid)
Other components to be considered as part of start-
ing system are:
²Battery
²Battery cables
²Ignition switch and key lock cylinder
²Clutch pedal position switch (manual transmis-
sion)
²Park/neutral position switch (automatic trans-
mission)
²Wire harnesses and connections.
The Battery, Starting, and Charging systems oper-
ate in conjunction with one another, and must be
tested as a complete system. For correct operation of
starting/charging systems, all components used in
these 3 systems must perform within specifications.
When attempting to diagnose any of these systems, it
is important that you keep their interdependency in
mind.
The diagnostic procedures used in each of these
groups include the most basic conventional diagnostic
methods, to the more sophisticated On-Board Diag-
nostics (OBD) built into the Powertrain Control Mod-
ule (PCM). Use of an induction-type milliampere
ammeter, volt/ohmmeter, battery charger, carbon pile
rheostat (load tester), and 12-volt test lamp may be
required.
Certain starting system components are monitored
by the PCM and may produce a Diagnostic TroubleCode (DTC). Refer to Diagnostic Trouble Codes in
Emission Control for a list of codes.OPERATION
The starting system components form two separate
circuits. A high-amperage feed circuit that feeds the
starter motor between 150 and 350 amperes (700
amperes - diesel engine), and a low-amperage control
circuit that operates on less than 20 amperes. The
high-amperage feed circuit components include the
battery, the battery cables, the contact disc portion of
the starter solenoid, and the starter motor. The low-
amperage control circuit components include the igni-
tion switch, the clutch pedal position switch (manual
transmission), the park/neutral position switch (auto-
matic transmission), the starter relay, the electro-
magnetic windings of the starter solenoid, and the
connecting wire harness components.
If the vehicle is equipped with a manual transmis-
sion, it has a clutch pedal position switch installed in
series between the ignition switch and the coil bat-
tery terminal of the starter relay. This normally open
switch prevents the starter relay from being ener-
gized when the ignition switch is turned to the Start
position, unless the clutch pedal is depressed. This
feature prevents starter motor operation while the
clutch disc and the flywheel are engaged. The starter
relay coil ground terminal is always grounded on
vehicles with a manual transmission.
If the vehicle is equipped with an automatic trans-
mission, battery voltage is supplied through the low-
amperage control circuit to the coil battery terminal
of the starter relay when the ignition switch is
turned to the Start position. The park/neutral posi-
tion switch is installed in series between the starter
relay coil ground terminal and ground. This normally
8F - 28 STARTINGDR

open switch prevents the starter relay from being
energized and the starter motor from operating
unless the automatic transmission gear selector is in
the Neutral or Park positions.
When the starter relay coil is energized, the nor-
mally open relay contacts close. The relay contacts
connect the relay common feed terminal to the relay
normally open terminal. The closed relay contacts
energize the starter solenoid coil windings.
The energized solenoid pull-in coil pulls in the sole-
noid plunger. The solenoid plunger pulls the shift
lever in the starter motor. This engages the starter
overrunning clutch and pinion gear with the starter
ring gear.
As the solenoid plunger reaches the end of its
travel, the solenoid contact disc completes the high-
amperage starter feed circuit and energizes the sole-
noid plunger hold-in coil. Current now flows between
the solenoid battery terminal and the starter motor,
energizing the starter.
Once the engine starts, the overrunning clutch pro-
tects the starter motor from damage by allowing thestarter pinion gear to spin faster than the pinion
shaft. When the ignition switch is released to the On
position, the starter relay coil is de-energized. This
causes the relay contacts to open. When the relay
contacts open, the starter solenoid plunger hold-in
coil is de-energized.
When the solenoid plunger hold-in coil is de-ener-
gized, the solenoid plunger return spring returns the
plunger to its relaxed position. This causes the con-
tact disc to open the starter feed circuit, and the shift
lever to disengage the overrunning clutch and pinion
gear from the starter ring gear.
DIAGNOSIS AND TESTING - STARTING
SYSTEM
The battery, starting, and charging systems oper-
ate in conjunction with one another, and must be
tested as a complete system. For correct starting/
charging system operation, all of the components
involved in these 3 systems must perform within
specifications.
Starting System Diagnosis
CONDITION POSSIBLE CAUSE CORRECTION
STARTER FAILS TO
OPERATE.1. Battery discharged or
faulty.1. Refer to Battery. Charge or replace battery, if required.
2. Starting circuit wiring
faulty.2. Refer to 8, Wiring Diagrams. Test and repair starter
feed and/or control circuits, if required.
3. Starter relay faulty. 3. Refer to Starter Relay in Diagnosis and Testing.
Replace starter relay if required.
4. Ignition switch faulty. 4. Refer to Ignition Switch and Key Lock Cylinder.
Replace ignition switch if required.
5. Clutch pedal position
switch faulty.5. Refer to Clutch Pedal Position Switch.
6. Park/Neutral position
switch faulty or
misadjusted.6. Refer to Park/Neutral Position Switch. Replace
park/neutral position switch if required.
7. Starter solenoid faulty. 7. Refer to Starter Motor. Replace starter motor assembly
if required.
8. Starter motor faulty. 8. If all other starting system components and circuits test
OK, replace starter motor.
STARTER ENGAGES,
FAILS TO TURN
ENGINE.1. Battery discharged or
faulty.1. Refer to Battery. Charge or replace battery if required.
2. Starting circuit wiring
faulty.2. Refer to 8, Wiring Diagrams. Test and repair starter
feed and/or control circuits if required.
3. Starter motor faulty. 3. If all other starting system components and circuits test
OK, replace starter motor assembly.
4. Engine seized. 4. Refer to Engine Diagnosis in the Diagnosis and Testing
section of 9, Engine.
DRSTARTING 8F - 29
STARTING (Continued)

Starting System Diagnosis
CONDITION POSSIBLE CAUSE CORRECTION
STARTER ENGAGES,
SPINS OUT BEFORE
ENGINE STARTS.1. Starter ring gear faulty. 1. Refer to Starter Motor Removal and Installation.
Remove starter motor to inspect starter ring gear.
Replace starter ring gear if required.
2. Starter motor faulty. 2. If all other starting system components and circuits test
OK, replace starter motor assembly.
STARTER DOES NOT
DISENGAGE.1. Starter motor
improperly installed.1. Refer to Starter Motor Removal and Installation.
Tighten starter mounting hardware to correct torque
specifications.
2. Starter relay faulty. 2. Refer to Starter Relay Diagnosis and Testing. Replace
starter relay if required.
3. Ignition switch faulty. 3. Refer to Ignition Switch and Key Lock Cylinder.
Replace ignition switch if required.
4. Starter motor faulty. 4. If all other starting system components and circuits test
OK, replace starter motor.
INSPECTION
For complete starter wiring circuit diagrams, refer
to 8, Wiring Diagrams. Before removing any unit
from starting system for repair or diagnosis, perform
the following inspections:
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO 8, PASSIVE RESTRAINT SYS-
TEMS, 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 DEPLOY-
MENT AND POSSIBLE PERSONAL INJURY.
²Battery- Visually inspect battery for indica-
tions of physical damage and loose or corroded cable
connections. Determine state-of-charge and cranking
capacity of battery. Charge or replace battery if
required. Refer toBatteryin 8, Battery.Note: If
equipped with diesel engine, a dual battery sys-
tem may be used, and both batteries must be
inspected.
²Ignition Switch- Visually inspect ignition
switch for indications of physical damage and loose
or corroded wire harness connections. Refer toIgni-
tion Switch and Key Lock Cylinder.
²Clutch Pedal Position Switch- If equipped
with manual transmission, visually inspect clutch
pedal position switch for indications of physical dam-
age and loose or corroded wire harness connections.
Refer toClutch Pedal Position Switchin 6,
Clutch.
²Park/Neutral Position Switch- If equipped
with automatic transmission, visually inspect park/
neutral position switch for indications of physical
damage and loose or corroded wire harness connec-tions. Refer toPark/Neutral Position Switchin
21, Transmission.
²Starter Relay- Visually inspect starter relay
for indications of physical damage and loose or cor-
roded wire harness connections.
²Starter Motor- Visually inspect starter motor
for indications of physical damage and loose or cor-
roded wire harness connections.
²Starter Solenoid- Visually inspect starter sole-
noid for indications of physical damage and loose or
corroded wire harness connections.
²Wiring- Visually inspect wire harnesses for
damage. Repair or replace any faulty wiring, as
required. Refer to 8, Wiring Diagrams.
TESTING
COLD CRANKING TEST
For complete starter wiring circuit diagrams, refer
to 8, Wiring Diagrams. The battery must be fully-
charged and load-tested before proceeding. Refer to
Batteryin 8, Battery.
(1) Connect volt-ampere tester to battery terminals
(Fig. 1). See instructions provided by manufacturer of
volt-ampere tester being used.Note: Certain diesel
equipped models use dual batteries. If equipped
with dual battery system, tester should be con-
nected to battery on left side of vehicle only.
Also, tester current reading must be taken from
positive battery cable lead that connects to
starter motor.
(2) Fully engage parking brake.
(3) If equipped with manual transmission, place
gearshift selector lever in Neutral position and block
clutch pedal in fully depressed position. If equipped
8F - 30 STARTINGDR
STARTING (Continued)