2002 DODGE RAM ignition

GROUP TAB LOCATOR
Introduction
0Lubrication & Maintenance
2Suspension
3Differential & Driveline
5Brakes
6Clutch
7Cooling
8AAudio
8BChime/Buzzer
8EElectronic Control Modules
8FEngine Systems
8GHeated Systems
8HHorn
8IIgnition Control
8JInstrument Cluster
8LLamps
8MMessage Systems
8NPower Systems
8ORestraints
8PSpeed Control
8QVehicle Theft Security
8RWipers/Washers
8WWiring
9Engine
11Exhaust System
13Frame & Bumpers
14Fuel System
19Steering
21Transmission and Transfer Case
22Tires/Wheels
23Body
24Heating & Air Conditioning
25Emissions Control
Component and System Index
Service Manual Comment Forms (Rear of Manual)
NOTE: For New Vehicle Preparation
information, see the separate
publication, 81-170-00003.

²The use of leaded gas is prohibited by Federal
law. Using leaded gasoline can impair engine perfor-
mance, damage the emission control system, and
could result in loss of warranty coverage.
²An out-of-tune engine, or certain fuel or ignition
malfunctions, can cause the catalytic converter to
overheat. If you notice a pungent burning odor or
some light smoke, your engine may be out of tune or
malfunctioning and may require immediate service.
Contact your dealer for service assistance.
²When pulling a heavy load or driving a fully
loaded vehicle when the humidity is low and the tem-
perature is high, use a premium unleaded fuel to
help prevent spark knock. If spark knock persists,
lighten the load, or engine piston damage may result.
²The use of fuel additives which are now being
sold as octane enhancers is not recommended. Most
of these products contain high concentrations of
methanol. Fuel system damage or vehicle perfor-
mance problems resulting from the use of such fuels
or additives is not the responsibility of
DaimlerChrysler Corporation and may not be covered
under the new vehicle warranty.
NOTE: Intentional tampering with emissions control
systems can result in civil penalties being assessed
against you.
DESCRIPTION - FUEL REQUIREMENTS -
DIESEL ENGINE
DESCRIPTION
WARNING: Do not use alcohol or gasoline as a fuel
blending agent. They can be unstable under certain
conditions and hazardous or explosive when mixed
with diesel fuel.
Use good quality diesel fuel from a reputable sup-
plier in your Dodge truck. For most year-round ser-
vice, number 2 diesel fuel meeting ASTM
specification D-975 will provide good performance. If
the vehicle is exposed to extreme cold (below 0ÉF/-
18ÉC), or is required to operate at colder-than-normal
conditions for prolonged periods, use climatized No. 2
diesel fuel or dilute the No. 2 diesel fuel with 50%
No. 1 diesel fuel. This will provide better protection
from fuel gelling or wax-plugging of the fuel filters.
Diesel fuel is seldom completely free of water. To
prevent fuel system trouble, including fuel line freez-
ing in winter, drain the accumulated water from the
fuel/water separator using the fuel/water separator
drain provided. If you buy good-quality fuel and fol-
low the cold-weather advice above, fuel conditioners
should not be required in your vehicle. If available in
your area, a high cetane ªpremiumº diesel fuel mayoffer improved cold starting and warm-up perfor-
mance.
DESCRIPTION - ENGINE COOLANT
WARNING: ANTIFREEZE IS AN ETHYLENE GLYCOL
BASE COOLANT AND IS HARMFUL IF SWAL-
LOWED OR INHALED. IF SWALLOWED, DRINK
TWO GLASSES OF WATER AND INDUCE VOMIT-
ING. IF INHALED, MOVE TO FRESH AIR AREA.
SEEK MEDICAL ATTENTION IMMEDIATELY. DO NOT
STORE IN OPEN OR UNMARKED CONTAINERS.
WASH SKIN AND CLOTHING THOROUGHLY AFTER
COMING IN CONTACT WITH ETHYLENE GLYCOL.
KEEP OUT OF REACH OF CHILDREN. DISPOSE OF
GLYCOL BASE COOLANT PROPERLY, CONTACT
YOUR DEALER OR GOVERNMENT AGENCY FOR
LOCATION OF COLLECTION CENTER IN YOUR
AREA. DO NOT OPEN A COOLING SYSTEM WHEN
THE ENGINE IS AT OPERATING TEMPERATURE OR
HOT UNDER PRESSURE, PERSONAL INJURY CAN
RESULT. AVOID RADIATOR COOLING FAN WHEN
ENGINE COMPARTMENT RELATED SERVICE IS
PERFORMED, PERSONAL INJURY CAN RESULT.
CAUTION: Use of Propylene Glycol based coolants
is not recommended, as they provide less freeze
protection and less corrosion protection.
The cooling system is designed around the coolant.
The coolant must accept heat from engine metal, in
the cylinder head area near the exhaust valves and
engine block. Then coolant carries the heat to the
radiator where the tube/fin radiator can transfer the
heat to the air.
The use of aluminum cylinder blocks, cylinder
heads, and water pumps requires special corrosion
protection. MopartAntifreeze/Coolant, 5
Year/100,000 Mile Formula (MS-9769), or the equiva-
lent ethylene glycol base coolant with organic corro-
sion inhibitors (called HOAT, for Hybrid Organic
Additive Technology) is recommended. This coolant
offers the best engine cooling without corrosion when
mixed with 50% Ethylene Glycol and 50% distilled
water to obtain a freeze point of -37ÉC (-35ÉF). If it
loses color or becomes contaminated, drain, flush,
and replace with fresh properly mixed coolant solu-
tion.
CAUTION: MoparTAntifreeze/Coolant, 5
Year/100,000 Mile Formula (MS-9769) may not be
mixed with any other type of antifreeze. Mixing of
coolants other than specified (non-HOAT or other
HOAT), may result in engine damage that may not
be covered under the new vehicle warranty, and
decreased corrosion protection.
BR/BELUBRICATION & MAINTENANCE 0 - 3
FLUID TYPES (Continued)

TO JUMP START A DISABLED VEHICLE:
(1) Raise hood on disabled vehicle and visually
inspect engine compartment for:
²Battery cable clamp condition, clean if necessary.
²Frozen battery.
²Yellow or bright color test indicator, if equipped.
²Low battery fluid level.
²Generator drive belt condition and tension.
²Fuel fumes or leakage, correct if necessary.
CAUTION: If the cause of starting problem on dis-
abled vehicle is severe, damage to booster vehicle
charging system can result.
(2) When using another vehicle as a booster
source, park the booster vehicle within cable reach.
Turn off all accessories, set the parking brake, place
the automatic transmission in PARK or the manual
transmission in NEUTRAL and turn the ignition
OFF.
(3) On disabled vehicle, place gear selector in park
or neutral and set park brake. Turn off all accesso-
ries.
(4) Connect jumper cables to booster battery. RED
clamp to positive terminal (+). BLACK clamp to neg-
ative terminal (-). DO NOT allow clamps at opposite
end of cables to touch, electrical arc will result.
Review all warnings in this procedure.
(5) On disabled vehicle, connect RED jumper cable
clamp to positive (+) terminal. Connect BLACK
jumper cable clamp to engine ground as close to the
ground cable attaching point as possible (Fig. 7)and
(Fig. 8).
(6) Start the engine in the vehicle which has the
booster battery, let the engine idle a few minutes,
then start the engine in the vehicle with the dis-
charged battery.
CAUTION: Do not crank starter motor on disabled
vehicle for more than 15 seconds, starter will over-
heat and could fail.
(7) Allow battery in disabled vehicle to charge to
at least 12.4 volts (75% charge) before attempting to
start engine. If engine does not start within 15 sec-
onds, stop cranking engine and allow starter to cool
(15 min.), before cranking again.
DISCONNECT CABLE CLAMPS AS FOLLOWS:
²Disconnect BLACK cable clamp from engine
ground on disabled vehicle.²When using a Booster vehicle, disconnect
BLACK cable clamp from battery negative terminal.
Disconnect RED cable clamp from battery positive
terminal.
²Disconnect RED cable clamp from battery posi-
tive terminal on disabled vehicle.
Fig. 7 Jumper Cable Clamp ConnectionsÐGas
Engine
1 - NEGATIVE OR GROUND CABLE CONNECTION
2 - POSITIVE CABLE CONNECTION
3 - BATTERY
Fig. 8 Jumper Cable Clamp ConnectionsÐDiesel
Engine
1 - POSITIVE CABLE CONNECTION
2 - BATTERY
3 - NEGATIVE OR GROUND CABLE CONNECTION
0 - 8 LUBRICATION & MAINTENANCEBR/BE
JUMP STARTING (Continued)

OPERATION
Battery voltage is supplied to the CAB when a
speed of 15 miles per hour is reached. The CAB per-
forms a system initialization procedure at this point.
Initialization consists of a static and dynamic self
check of system electrical components.
The static and dynamic checks occurs at ignition
start up. During the dynamic check, the CAB briefly
cycles the pump and solenoids to verify operation. An
audible noise may be heard during this self check.
This noise should be considered normal.
If an ABS component exhibits a fault during ini-
tialization, the CAB illuminates the amber warning
light and registers a fault code in the microprocessor
memory.
The CAB monitors wheel speed sensor inputs con-
tinuously while the vehicle is in motion. However,
the CAB will not activate any ABS components as
long as sensor inputs indicate normal braking.
During normal braking, the master cylinder, power
booster and wheel brake units all function as they
would in a vehicle without ABS. The HCU compo-
nents are not activated.
The purpose of the antilock system is to prevent
wheel lockup during periods of high wheel slip. Pre-
venting lockup helps maintain vehicle braking action
and steering control.
The antilock CAB activates the system whenever
sensor signals indicate periods of wheel slip. Periods
of wheel slip occur when brake stops involve high
pedal pressure and rate of vehicle deceleration.
The antilock system prevents lockup during a
wheel slip condition by modulating fluid apply pres-
sure to the wheel brake units.
Brake fluid apply pressure is modulated according
to wheel speed, degree of slip and rate of decelera-
tion. Sensors at each front wheel convert wheel speed
into electrical signals. These signals are transmitted
to the CAB for processing and determination of
wheel slip and deceleration rate.
The ABS system has three fluid pressure control
channels. The front brakes are controlled separately
and the rear brakes in tandem. A speed sensor input
signal indicating a wheel slip condition activates the
CAB antilock program.
There are Two solenoid valves (Isolation and Dump
valve) which are used in each antilock control chan-
nel. The valves are all located within the HCU valve
body and work in pairs to either increase, hold, or
decrease apply pressure as needed in the individual
control channels.
During an ABS stop the ISO valve actuates, Stop-
ping anymore pressure build Ðup to the calipers.
Then the Dump valve dumps off pressure until the
wheel unlocks. This will continue until the wheels
quit slipping altogether.
DIAGNOSIS AND TESTING - ANTILOCK
BRAKES
The ABS brake system performs several self-tests
every time the ignition switch is turned on and the
vehicle is driven. The CAB monitors the systems
input and output circuits to verify the system is oper-
ating correctly. If the on board diagnostic system
senses that a circuit is malfunctioning the system
will set a trouble code in its memory.
NOTE: An audible noise may be heard during the
self-test. This noise should be considered normal.
NOTE: The MDS or DRB III scan tool is used to
diagnose the ABS system. For additional informa-
tion refer to the Antilock Brake section in Group
8W. For test procedures refer to the Chassis Diag-
nostic Manual.
STANDARD PROCEDURE
STANDARD PROCEDURE - RWAL SERVICE
PRECAUTIONS
The RWAL uses an electronic control module, the
CAB. This module is designed to withstand normal
current draws associated with vehicle operation.
Care must be taken to avoid overloading the CAB
circuits.In testing for open or short circuits, do
not ground or apply voltage to any of the cir-
cuits unless instructed to do so for a diagnostic
procedure.These circuits should only be tested
using a high impedance multi-meter or the DRB
tester as described in this section. Power should
never be removed or applied to any control module
with the ignition in the ON position. Before removing
or connecting battery cables, fuses, or connectors,
always turn the ignition to the OFF position.
CAUTION: Use only factory wiring harnesses. Do
not cut or splice wiring to the brake circuits. The
addition of after-market electrical equipment (car
phone, radar detector, citizen band radio, trailer
lighting, trailer brakes, ect.) on a vehicle equipped
with antilock brakes may affect the function of the
antilock brake system.
STANDARD PROCEDURE - BLEEDING ABS
BRAKE SYSTEM
ABS system bleeding requires conventional bleed-
ing methods plus use of the DRB scan tool. The pro-
cedure involves performing a base brake bleeding,
followed by use of the scan tool to cycle and bleed the
5 - 36 BRAKES - ABSBR/BE
BRAKES - ABS (Continued)

NOTE: Check the sensor wire routing. Be sure the
wire is clear of all chassis components and is not
twisted or kinked at any spot.
(6) Install the tire and wheel assembly.
(7) Remove the support and lower the vehicle.
(8) Reconnect the ABS wheel speed sensor wire
electrical connector inside the engine compartment.
(9) Apply the brakes several times to seat the
brake shoes and caliper piston. Do not move the vehi-
cle until a firm brake pedal is obtained.
(10) Verify the wheel speed sensor operation with
a scan tool.
REAR WHEEL SPEED SENSOR
DIAGNOSIS AND TESTING - REAR WHEEL
SPEED SENSOR
Diagnosis of base brake conditions which are
mechanical in nature should be performed first. This
includes brake noise, lack of power assist, parking
brake, or vehicle vibration during normal braking.
The Antilock brake system performs several self-
tests every time the ignition switch is turned on and
the vehicle is driven. The CAB monitors the system
inputs and outputs circuits to verify the system is
operating properly. If the CAB senses a malfunction
in the system it will set a DTC into memory and trig-
ger the warning lamp.
NOTE: The MDS or DRB III scan tool is used to
diagnose the Antilock Brake system. For test proce-
dures refer to the Chassis Diagnostic Manual.
REMOVAL
(1) Raise vehicle on hoist.
(2) Remove brake line mounting nut and remove
the brake line from the sensor stud.
(3) Remove mounting stud from the sensor and
shield (Fig. 6) .
(4) Remove sensor and shield from differential
housing.
(5) Disconnect sensor wire harness and remove
sensor.
INSTALLATION
(1) Connect harness to sensor.Be sure seal is
securely in place between sensor and wiring
connector.
(2) Install O-ring on sensor (if removed).
(3) Insert sensor in differential housing.
(4) Install sensor shield.
(5) Install the sensor mounting stud and tighten to
24 N´m (18 ft. lbs.).(6) Install the brake line on the sensor stud and
install the nut.
(7) Lower vehicle.
HCU (HYDRAULIC CONTROL
UNIT)
DESCRIPTION
The hydraulic control unit (HCU) consists of a
valve body, pump, two accumulators and a motor.
The assembly is mounted on the driverside inner
fender under the hood.
OPERATION
The pump, motor, and accumulators are combined
into an assembly attached to the valve body. The
accumulators store the extra fluid which had to be
dumped from the brakes. This is done to prevent the
wheels from locking up. The pump provides the fluid
volume needed and is operated by a DC type motor.
The motor is controlled by the CAB.
During normal braking, the HCU solenoid valves
and pump are not activated. The master cylinder and
power booster operate the same as a vehicle without
an ABS brake system.
The valve body contains the solenoid valves. The
valves modulate brake pressure during antilock brak-
ing and are controlled by the CAB.
The HCU provides three channel pressure control
to the front and rear brakes. One channel controls
the rear wheel brakes in tandem. The two remaining
channels control the front wheel brakes individually.
Fig. 6 Rear Speed Sensor Mounting
1 - WHEEL SPEED SENSOR
2 - AXLE
5 - 40 BRAKES - ABSBR/BE
FRONT WHEEL SPEED SENSOR (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
8. Incorrect coolant concentration 8. Check coolant. (Refer to
LUBRICATION & MAINTENANCE/
FLUID TYPES - DESCRIPTION).
9. Coolant not flowing through
system9. Check for coolant flow at radiator
filler neck with some coolant
removed, engine warm and
thermostat open. Coolant should be
observed flowing through radiator. If
flow is not observed, determine area
of obstruction and repair as
necessary.
10. Radiator or A/C condenser fins
are dirty or clogged.10. Remove insects and debris.
(Refer to 7 - COOLING -
STANDARD PROCEDURE).
11. Radiator core is corroded or
plugged.11. Have radiator re-cored or
replaced.
12. Aftermarket A/C installed
without proper radiator.12. Install proper radiator.
13. Fuel or ignition system
problems.13. Refer to 14 - Fuel System or 8 -
Electrical for diagnosis and testing
procedures.
14. Dragging brakes. 14. Check and correct as
necessary. (Refer to 5 - BRAKES -
DIAGNOSIS AND TESTING) for
correct procedures.
15. Bug screen or cardboard is
being used, reducing airflow.15. Remove bug screen or
cardboard.
16. Thermostat partially or
completely shut.16. Check thermostat operation and
replace as necessary. (Refer to 7 -
COOLING/ENGINE/ENGINE
COOLANT THERMOSTAT -
REMOVAL).
17. Viscous fan drive not operating
properly.17. Check fan drive operation and
replace as necessary. (Refer to 7 -
COOLING/ENGINE/FAN DRIVE
VISCOUS CLUTCH - REMOVAL).
18. Cylinder head gasket leaking. 18. Check for cylinder head gasket
leaks. (Refer to 7 - COOLING -
DIAGNOSIS AND TESTING).
19. Heater core leaking. 19. Check heater core for leaks.
(Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING -
DIAGNOSIS AND TESTING).
Repair as necessary.
BR/BECOOLING 7 - 9
COOLING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
COOLANT LOSS TO THE
GROUND WITHOUT PRESSURE
CAP BLOWOFF. GAUGE READING
HIGH OR HOT1. Coolant leaks in radiator, cooling
system hoses, water pump or
engine.1. Pressure test and repair as
necessary. (Refer to 7 - COOLING -
DIAGNOSIS AND TESTING).
DETONATION OR PRE-IGNITION
(NOT CAUSED BY IGNITION
SYSTEM). GAUGE MAY OR MAY
NOT BE READING HIGH1. Engine overheating. 1. Check reason for overheating
and repair as necessary.
2. Freeze point of coolant not
correct. Mixture is too rich or too
lean.2. Check coolant concentration.
(Refer to LUBRICATION &
MAINTENANCE/FLUID TYPES -
DESCRIPTION).
HOSE OR HOSES COLLAPSE
WHILE ENGINE IS RUNNING1. Vacuum created in cooling
system on engine cool-down is not
being relieved through coolant
reserve/overflow system.1. (a) Radiator cap relief valve
stuck. (Refer to 7 - COOLING/
ENGINE/RADIATOR PRESSURE
CAP - DIAGNOSIS AND TESTING).
Replace if necessary
(b) Hose between coolant
reserve/overflow tank and radiator is
kinked. Repair as necessary.
(c) Vent at coolant reserve/overflow
tank is plugged. Clean vent and
repair as necessary.
(d) Reserve/overflow tank is
internally blocked or plugged. Check
for blockage and repair as
necessary.
NOISY VISCOUS FAN/DRIVE 1. Fan blades loose. 1. Replace fan blade assembly.
(Refer to 7 - COOLING/ENGINE/
RADIATOR FAN - REMOVAL)
2. Fan blades striking a surrounding
object.2. Locate point of fan blade contact
and repair as necessary.
3. Air obstructions at radiator or air
conditioning condenser.3. Remove obstructions and/or
clean debris or insects from radiator
or A/C condenser.
4. Thermal viscous fan drive has
defective bearing.4. Replace fan drive. Bearing is not
serviceable. (Refer to 7 - COOLING/
ENGINE/FAN DRIVE VISCOUS
CLUTCH - REMOVAL).
5. A certain amount of fan noise
may be evident on models
equipped with a thermal viscous fan
drive. Some of this noise is normal.5. (Refer to 7 - COOLING/ENGINE/
FAN DRIVE VISCOUS CLUTCH -
DESCRIPTION) for an explanation
of normal fan noise.
BR/BECOOLING 7 - 11
COOLING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
2. Thermal viscous fan drive not
working.2. Check fan drive. (Refer to 7 -
COOLING/ENGINE/FAN DRIVE
VISCOUS CLUTCH - DIAGNOSIS
AND TESTING)
3. Air seals around radiator
damaged or missing.3. Inspect air seals, repair or
replace as necessary.
INADEQUATE HEATER
PERFORMANCE. GUAGE MAY OR
MAY NOT READ LOW.1. Heavy duty cooling system, and
cooler ambient temperatures.1. None. Normal condition.
2. Obstruction in heater hoses. 2. Remove hoses, remove
obstruction.
3. Water pump damaged. 3. Replace water pump.
HEAT ODOR 1. Damaged or missing drive line
heat shields.1. Repair or replace damaged or
missing heat shields.
2. Thermal viscous fan drive
damaged.2. Check thermal viscous fan drive.
(Refer to 7 - COOLING/ENGINE/
FAN DRIVE VISCOUS CLUTCH -
DIAGNOSIS AND TESTING)
STANDARD PROCEDURE
STANDARD PROCEDURE - DRAINING COOLING
SYSTEM 5.9L/8.0L ENGINES
WARNING: DO NOT REMOVE CYLINDER BLOCK
DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-
COCK WITH SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM COOLANT CAN OCCUR.
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
(1) Remove radiator pressure cap.
(2) Loosen radiator petcock.
(3) Remove cylinder block drain plugs. Refer to
(Fig. 7).
STANDARD PROCEDUREÐDRAINING COOLING
SYSTEM 5.9L DIESEL ENGINE
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAIN PLUG WITH SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR.
DO NOT WASTE reusable coolant. If the solution
is clean, drain the coolant into a clean container for
reuse.
(1) Start the engine and place the heater control
temperature selector in the Full-On position. Vacuum
is needed to actuate the heater controls.(2) Turn the ignition off.
(3) Do not remove radiator cap when draining cool-
ant from reserve/overflow tank. Open radiator drain
plug and when tank is empty, remove radiator cap. If
the coolant reserve/overflow tank does not drain,
(Refer to 7 - COOLING - DIAGNOSIS AND TEST-
ING). The coolant need not be removed from tank
unless the system is being refilled with fresh mix-
ture.
(4) Remove radiator pressure cap.
Fig. 7 Cylinder Block Drain Plug - 5.9L Engines
1 - BLOCK DRAIN PLUG
BR/BECOOLING 7 - 15
COOLING (Continued)