2003 DODGE RAM engine system

Downstream Sensor - Federal Emissions
Package :The downstream oxygen sensor (1/2) is
also used to determine the correct air-fuel ratio. As
the oxygen content changes at the downstream sen-
sor, the PCM calculates how much air-fuel ratio
change is required. The PCM then looks at the
upstream oxygen sensor voltage and changes fuel
delivery until the upstream sensor voltage changes
enough to correct the downstream sensor voltage
(oxygen content).
The downstream oxygen sensor also provides an
input to determine catalytic convertor efficiency.
Upstream Sensors - California Emissions
Package :Two upstream sensors are used (1/1 and
2/1). The 1/1 sensor is the first sensor to receive
exhaust gases from the #1 cylinder. They provide an
input voltage to the PCM. The input tells the PCM
the oxygen content of the exhaust gas. The PCM uses
this information to fine tune fuel delivery to main-
tain the correct oxygen content at the downstream
oxygen sensors. The PCM will change the air/fuel
ratio until the upstream sensors input a voltage that
the PCM has determined will make the downstream
sensors output (oxygen content) correct.
The upstream oxygen sensors also provide an input
to determine mini-catalyst efficiency. Main catalytic
convertor efficiency is not calculated with this pack-
age.
Downstream Sensors - California Emissions
Package :Two downstream sensors are used (1/2
and 2/2). The downstream sensors are used to deter-
mine the correct air-fuel ratio. As the oxygen content
changes at the downstream sensor, the PCM calcu-
lates how much air-fuel ratio change is required. The
PCM then looks at the upstream oxygen sensor volt-
age, and changes fuel delivery until the upstream
sensor voltage changes enough to correct the down-
stream sensor voltage (oxygen content).
The downstream oxygen sensors also provide an
input to determine mini-catalyst efficiency. Main cat-
alytic convertor efficiency is not calculated with this
package.
Engines equipped with either a downstream sen-
sor(s), or a post-catalytic sensor, will monitor cata-
lytic convertor efficiency. If efficiency is below
emission standards, the Malfunction Indicator Lamp
(MIL) will be illuminated and a Diagnostic Trouble
Code (DTC) will be set. Refer to Monitored Systems
in Emission Control Systems for additional informa-
tion.
REMOVAL
CAUTION: Never apply any type of grease to the
oxygen sensor electrical connector, or attempt any
soldering of the sensor wiring harness.Refer to (Fig. 39) or (Fig. 40) for typical O2S (oxy-
gen sensor) locations.
WARNING: THE EXHAUST MANIFOLD, EXHAUST
PIPES AND CATALYTIC CONVERTER BECOME
VERY HOT DURING ENGINE OPERATION. ALLOW
ENGINE TO COOL BEFORE REMOVING OXYGEN
SENSOR.
(1) Raise and support vehicle.
(2) Disconnect wire connector from O2S sensor.
CAUTION: When disconnecting sensor electrical
connector, do not pull directly on wire going into
sensor.
(3) Remove O2S sensor with an oxygen sensor
removal and installation tool.
(4) Clean threads in exhaust pipe using appropri-
ate tap.
Fig. 39 O2 SENSOR SYSTEM - WITH 4 SENSORS
Fig. 40 O2 SENSOR SYSTEM - WITH 2 SENSORS
1 - POST CATALYST OXYGEN SENSOR (1/3)
2 - PRE-CATALYST OXYGEN SENSOR (1/2)
14 - 44 FUEL INJECTION - GASDR
OXYGEN SENSOR (Continued)

FUEL DELIVERY - DIESEL
DESCRIPTION - DIESEL FUEL SYSTEM
The fuel system used on the Cummins engine is an
electronically controlled, Bosch HPCR (High-Pressure
Common Rail) system. The HPCR system consists of
five main components:
²Electric Fuel Transfer (lift) Pump
²Fuel Pump/Gear Pump (attached to fuel injec-
tion pump)
²High-Pressure Fuel Injection Pump
²Fuel Injection Rail
²Fuel Injectors
Also to be considered as part of the overall fuel
system are:
²Accelerator Pedal
²Air Cleaner Housing/Element
²Fuel Drain Manifold (passage)
²Fuel Drain Valve (at filter)
²Fuel Filter/Water Separator
²Fuel Heater
²Fuel Heater Relay
²Fuel Level (gauge) Sending Unit
²Fuel Tank
²Fuel Tank Module (containing fuel gauge send-
ing unit and separate fuel filter located at bottom of
tank module)
²Fuel Tank Filler/Vent Tube Assembly
²Fuel Tank Filler Tube Cap
²Fuel Tubes/Lines/Hoses
²High-Pressure Fuel Injector Lines
²In-Tank Fuel Filter (at bottom of fuel tank mod-
ule)
²Low-Pressure Fuel Supply Lines
²Low-Pressure Fuel Return Line
²Overflow Valve
²Quick-Connect Fuel Line Fittings
²Throttle Cable
²Water Draining (maintenance)
²Water-In-Fuel (WIF) Sensor
The fuel injection pump supplies high pressure to
the fuel rail independent of engine speed. This high
pressure is then accumulated in the fuel rail. High
pressure fuel is constantly supplied to the injectors
by the fuel rail. The Engine Control Module (ECM)
controls the fueling and timing of the engine by actu-
ating the injectors.Fuel enters the system from the electric fuel trans-
fer (lift) pump, which is attached to the fuel filter
assembly. Fuel is forced through the fuel filter ele-
ment and then enters the Fuel Pump/Gear Pump,
which is attached to the rear of the fuel injection
pump. The Fuel Pump/Gear Pump is a low-pressure
pump and produce pressures ranging from 551.5 kpa
(80 psi) to 1241 kpa (180) psi. Fuel then enters the
fuel injection pump. Low pressure fuel is then sup-
plied to the FCA (Fuel Control Actuator).
The FCA is an electronically controlled solenoid
valve. The ECM controls the amount of fuel that
enters the high-pressure pumping chambers by open-
ing and closing the FCA based on a demanded fuel
pressure. The FPS (Fuel Pressure Sensor) on the fuel
rail provides the actual fuel pressure. When the
actuator is opened, the maximum amount of fuel is
being supplied to the fuel injection pump. Any fuel
that does not enter the injection pump is directed to
the overflow valve. The overflow valve regulates how
much excess fuel is used for lubrication of the pump
and how much is returned to the tank through the
drain manifold.
Fuel entering the injection pump is pressurized to
between 300 - 1600 bar by three radial pumping
chambers. The pressurized fuel is then supplied to
the fuel rail.
Some fuel system components are shown in.
WARNING: HIGH-PRESSURE FUEL LINES DELIVER
DIESEL FUEL UNDER EXTREME PRESSURE FROM
THE INJECTION PUMP TO THE FUEL INJECTORS.
THIS MAY BE AS HIGH AS 160,000 KPA (23,206
PSI). USE EXTREME CAUTION WHEN INSPECTING
FOR HIGH-PRESSURE FUEL LEAKS. INSPECT FOR
HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF
CARDBOARD. HIGH FUEL INJECTION PRESSURE
CAN CAUSE PERSONAL INJURY IF CONTACT IS
MADE WITH THE SKIN.
Certain fuel system components can be found in
(Fig. 1), or (Fig. 2).
STANDARD PROCEDURE
STANDARD PROCEDURES - WATER DRAINING
AT FUEL FILTER
Refer to Fuel Filter/Water Separator removal/in-
stallation for procedures.
DRFUEL DELIVERY - DIESEL 14 - 57

STANDARD PROCEDURES - CLEANING FUEL
SYSTEM PARTS
CAUTION: Cleanliness cannot be overemphasized
when handling or replacing diesel fuel system com-
ponents. This especially includes the fuel injectors,
high-pressure fuel lines and fuel injection pump.
Very tight tolerances are used with these parts. Dirt
contamination could cause rapid part wear and pos-
sible plugging of fuel injector nozzle tip holes. This
in turn could lead to possible engine misfire.Always wash/clean any fuel system component
thoroughly before disassembly and then air dry.
Cap or cover any open part after disassembly.
Before assembly, examine each part for dirt, grease
or other contaminants and clean if necessary. When
installing new parts, lubricate them with clean
engine oil or clean diesel fuel only.
Fig. 1 DIESEL FUEL SYSTEM COMPONENTS
1 - ENGINE COOLANT TEMPERATURE (ECT) SENSOR 14 - FUEL SUPPLY LINE (LOW-PRESSURE, TO ENGINE)
2 - THROTTLE LEVER BELLCRANK AND APPS (ACCELERATOR
PEDAL POSITION SENSOR)15 - FUEL RETURN LINE CONNECTION (TO FUEL TANK)
3 - INTAKE MANIFOLD AIR HEATER/ELEMENTS 16 - FUEL DRAIN TUBE
4 - FUEL PRESSURE SENSOR 17 - OIL PRESSURE SENSOR
5 - FUEL LIMITING VALVE 18 - ENGINE CONTROL MODULE (ECM)
6 - HIGH-PRESSURE FUEL LINES 19 - FUEL INJECTION PUMP
7 - FUEL HEATER 20 - CRANKSHAFT POSITION (ENGINE SPEED) SENSOR
8 - HIGH-PRESSURE FUEL INJECTOR RAIL 21 - CAMSHAFT POSITION SENSOR (CMP)
9 - FUEL HEATER TEMPERATURE SENSOR (THERMOSTAT) 22 - FUEL CONTROL ACTUATOR (FCA)
10 - FUEL FILTER/WATER SEPARATOR 23 - CASCADE OVERFLOW VALVE
11 - FUEL TRANSFER (LIFT) PUMP
12 - FUEL DRAIN MANIFOLD
13 - DRAIN VALVE
14 - 58 FUEL DELIVERY - DIESELDR
FUEL DELIVERY - DIESEL (Continued)

STANDARD PROCEDURE - FUEL SYSTEM
PRIMING
A certain amount of air becomes trapped in the
fuel system when fuel system components on the
supply and/or high-pressure side are serviced or
replaced. Fuel system priming is accomplished using
the electric fuel transfer (lift) pump.
Servicing or replacing fuel system components usu-
ally will not require fuel system priming.
The fuel transfer (lift) pump is self-priming: When
the key is first turned on (without cranking engine),
the pump operates for approximately 2 seconds and
then shuts off. The pump will also operate for up to25 seconds after the starter is quickly engaged, and
then disengaged without allowing the engine to start.
The pump shuts off immediately if the key is on and
the engine stops running.
(1) Turn key to CRANK position and quickly
release key to ON position before engine starts. This
will operate fuel transfer pump for approximately 25
seconds.
(2) If the engine does not start after 25 seconds,
turn key OFF. Repeat previous step until engine
starts.
(3) Fuel system priming is now completed.
(4) Attempt to start engine. If engine will not
start, proceed to following steps.When engine does
start, it may run erratically and be noisy for a
few minutes. This is a normal condition.
CAUTION: Do not engage the starter motor for more
than 30 seconds at a time. Allow two minutes
between cranking intervals.
(5) Perform previous fuel priming procedure steps
using fuel transfer pump. Be sure fuel is present at
fuel tank.
(6) Crank the engine for 30 seconds at a time to
allow fuel system to prime.
WARNING: THE FUEL INJECTION PUMP SUPPLIES
EXTREMELY HIGH FUEL PRESSURE TO EACH INDI-
VIDUAL INJECTOR THROUGH THE HIGH-PRES-
SURE LINES. FUEL UNDER THIS AMOUNT OF
PRESSURE CAN PENETRATE THE SKIN AND
CAUSE PERSONAL INJURY. WEAR SAFETY GOG-
GLES AND ADEQUATE PROTECTIVE CLOTHING.
DO NOT LOOSEN FUEL FITTINGS WHILE ENGINE
IS RUNNING.
WARNING: ENGINE MAY START WHILE CRANKING
STARTER MOTOR.
Fig. 2 FUEL INJECTORS
1 - SOLENOID CONNECTIONS
2 - ROCKER HOUSING
3 - FUEL INJECTOR
4 - PASSTHROUGH CONNECTOR
DRFUEL DELIVERY - DIESEL 14 - 59
FUEL DELIVERY - DIESEL (Continued)

(b) Disconnect electrical connector.
(c) Remove two T-15 Torx head mounting screws
from fuel heater element.
(d) Remove fuel filter cover and filter element.
(e) Remove fuel heater.
(8)Drain Valve Replacement:The drain valve
assembly is located on the side of the fuel filter hous-
ing (Fig. 3) or (Fig. 4).
(a) Disconnect drain hose from the fuel drain
valve.
(b) Remove 4 drain valve mounting screws (T-15
Torx head).
(c) Remove drain valve from filter housing.
INSTALLATION
Refer to maintenance schedules for recommended
fuel filter replacement intervals.
(1) Thoroughly clean inside of filter housing, filter
cap and all related components.
(2)Fuel Filter:
(a)The engine has a self-priming low-pres-
sure fuel system. Refer to Standard Proce-
dures-Fuel System Priming.
(b) Install new o-ring to canister lid and lubri-
cate o-ring with 30W oil.
Fig. 3 FILTER HOUSING (EARLY)
1 - FILTER HOUSING
2 - FUEL HEATER AND THERMOSTAT
3 - FUEL HEATER MOUNTING SCREWS
4 - FUEL HEATER ELEC. CONNECTOR
5 - DRAIN VALVE
6 - DRAIN VALVE MOUNTING SCREWS
7 - DRAIN HOSE
8 - WIF SENSOR
9 - WIF SENSOR ELEC. CONNECTOR
Fig. 4 FILTER HOUSING (LATE)
1 - FILTER HOUSING
2 - FUEL HEATER AND THERMOSTAT
3 - FUEL HEATER MOUNTING SCREWS
4 - FUEL HEATER ELEC. CONNECTOR
5 - WIF SENSOR
6 - WIF SENSOR ELEC. CONNECTOR
7 - DRAIN HOSE
8 - DRAIN VALVE MOUNTING SCREWS
9 - DRAIN VALVE
Fig. 5 FILTER COVER (LID)
1 - FILTER COVER
2 - ATTACH SOCKET HERE
14 - 62 FUEL DELIVERY - DIESELDR
FUEL FILTER / WATER SEPARATOR (Continued)

heater. The heater can be check at room tempera-
ture. Operating range is 0.3 Ð 0.45 Ohms.
(3) Replace heater if resistance is not within oper-
ating range.
(4) If heater is within operating range, replace
heater thermostat.
REMOVAL
REMOVAL/INSTALLATION
The fuel heater/element/sensor assembly is located
inside of the fuel filter housing. Refer to Fuel Filter/
Water Separator Removal/Installation for procedures.
FUEL HEATER RELAY
DESCRIPTION
The fuel heater relay is located in Power Distribu-
tion Center (PDC) (Fig. 6). Refer to label on inside of
PDC cover for relay location.
OPERATION
Battery voltage to operate the fuel heater element
is supplied from the ignition switch through the fuel
heater relay.The fuel heater element and fuel
heater relay are not computer controlled.
REMOVAL
The fuel heater relay is located in the Power Dis-
tribution Center (PDC) (Fig. 7). Refer to label under
PDC cover for relay location.
(1) Remove PDC cover.
(2) Remove relay from PDC.(3) Check condition of relay terminals and PDC
connector terminals for damage or corrosion. Repair
if necessary before installing relay.
(4) Check for pin height (pin height should be the
same for all terminals within the PDC connector).
Repair if necessary before installing relay.
INSTALLATION
The fuel heater relay is located in the Power Dis-
tribution Center (PDC) (Fig. 7). Refer to label under
PDC cover for relay location.
(1) Install relay to PDC.
(2) Install cover to PDC.
FUEL INJECTION PUMP
DESCRIPTION
A Robert Bosch high-pressure fuel injection pump
is used. The pump is attached to the back of the tim-
ing gear cover at the left / rear side of the engine.
OPERATION
The fuel injection pump supplies high pressure to
the fuel rail independent of engine speed. This high
pressure is then accumulated in the fuel rail. High
pressure fuel is constantly supplied to the injectors
by the fuel rail. The Engine Control Module (ECM)
controls the fueling and timing of the engine by actu-
ating the injectors.
Fuel enters the system from the electric fuel trans-
fer (lift) pump, which is attached to the fuel filter
assembly. Fuel is forced through the fuel filter ele-
ment and then enters the Fuel Pump/Gear Pump,
which is attached to the rear of the fuel injection
Fig. 6 POWER DISTRIBUTION CENTER LOCATION
1 - CLIP
2 - BATTERY
3 - TRAY
4 - NEGATIVE CABLE
5 - POSITIVE CABLE
6 - CLIP
7 - FENDER INNER SHIELD
8 - POWER DISTRIBUTION CENTER
Fig. 7 POWER DISTRIBUTION CENTER LOCATION
1 - CLIP
2 - BATTERY
3 - TRAY
4 - NEGATIVE CABLE
5 - POSITIVE CABLE
6 - CLIP
7 - FENDER INNER SHIELD
8 - POWER DISTRIBUTION CENTER
14 - 64 FUEL DELIVERY - DIESELDR
FUEL HEATER (Continued)

pump. The Fuel Pump/Gear Pump is a low-pressure
pump and produce pressures ranging from 551.5 kpa
(80 psi) to 1241 kpa (180) psi. Fuel then enters the
fuel injection pump. Low pressure fuel is then sup-
plied to the FAC (Fuel Control Actuator).
The FAC is an electronically controlled solenoid
valve. The ECM controls the amount of fuel that
enters the high-pressure pumping chambers by open-
ing and closing the FAC based on a demanded fuel
pressure. The FPS (Fuel Pressure Sensor) on the fuel
rail provides the actual fuel pressure. When the
actuator is opened, the maximum amount of fuel is
being supplied to the fuel injection pump. Any fuel
that does not enter the injection pump is directed to
the overflow valve. The overflow valve regulates how
much excess fuel is used for lubrication of the pump
and how much is returned to the tank through the
drain manifold.
Fuel entering the injection pump is pressurized to
between 300 - 1600 bar by three radial pumping
chambers. The pressurized fuel is then supplied to
the fuel rail.
DIAGNOSIS AND TESTING - FUEL INJECTION
PUMP TIMING
With the Bosch injection pump, there are no
mechanical adjustments needed or necessary to
accomplish fuel injection timing. All timing and fuel
adjustments are electrically made by the engine
mounted Engine Control Module (ECM).
REMOVAL
CAUTION: Cleanliness cannot be overemphasized
when handling or replacing diesel fuel system com-
ponents. This especially includes the fuel injectors,
high-pressure fuel lines and fuel injection pump.
Very tight tolerances are used with these parts. Dirt
contamination could cause rapid part wear and pos-
sible plugging of fuel injector nozzle tip holes. This
in turn could lead to possible engine misfire.
Always wash/clean any fuel system component
thoroughly before disassembly and then air dry.
Cap or cover any open part after disassembly.
Before assembly, examine each part for dirt, grease
or other contaminants and clean if necessary. When
installing new parts, lubricate them with clean
engine oil or clean diesel fuel only.
(1) Disconnect both negative battery cables at both
batteries. Cover and isolate ends of both cables.
(2) Remove intake manifold air intake tube (above
injection pump) and its rubber connector hose (Fig.
8).
(3) The Engine Control Module (ECM) is mounted
to left side of engine (Fig. 9). Remove 5 ECM mount-ing bolts and position ECM for injection pump
removal.Do not disconnect wiring connectors
from ECM.
(4) Remove cooling fan shroud.
(5) Remove cooling fan assembly.
(6) Remove accessory drive belt.
(7) Thoroughly clean the rear of injection pump,
and attachment points for its 3 fuel lines (Fig. 10).
Also clean the opposite ends of these same 3 lines at
their attachment points.
(8) Disconnect Fuel Control Actuator (FCA) electri-
cal connector at rear of injection pump (Fig. 11).
(9) Remove fuel line (injection pump-to-overflow
valve).
(10) Remove fuel line (injection pump-to-fuel rail).
(11) Remove fuel line (injection pump-to-fuel filter
housing).
(12) Remove fuel pump drive gear access cover
(plate) with a 1/2 inch drive ratchet. Plate is
threaded to timing gear cover (Fig. 12).
(13) Remove fuel pump drive gear mounting nut
and washer.
(14) Attach C3428B, or L4407A (or equivalent)
gear puller (Fig. 13) to pump drive gear with 2 bolts,
and separate gear from pump (a keyway is not used
on this particular injection pump). Leave drive gear
hanging loose within timing gear cover.
(15) Remove 3 injection pump mounting nuts (Fig.
14), and remove pump from engine.
Fig. 8 INTAKE TUBE AND CONNECTING HOSE
1 - MANIFOLD ABOVE HEATERS
2 - RUBBER CONNECTING HOSE
3 - METAL INTAKE TUBE
4 - CLAMPS (2)
DRFUEL DELIVERY - DIESEL 14 - 65
FUEL INJECTION PUMP (Continued)

INSTALLATION
CAUTION: Cleanliness cannot be overemphasized
when handling or replacing diesel fuel system com-
ponents. This especially includes the fuel injectors,
high-pressure fuel lines and fuel injection pump.
Very tight tolerances are used with these parts. Dirt
contamination could cause rapid part wear and pos-
sible plugging of fuel injector nozzle tip holes. This
in turn could lead to possible engine misfire.
Always wash/clean any fuel system component
thoroughly before disassembly and then air dry.
Cap or cover any open part after disassembly.
Before assembly, examine each part for dirt, grease
or other contaminants and clean if necessary. When
installing new parts, lubricate them with clean
engine oil or clean diesel fuel only.
(1) Inspect pump mounting surfaces at pump and
mounting flange for nicks, cuts or damage. Inspect
o-ring surfaces for nicks, cuts or damage.
(2) Clean injection pump mounting flange at gear
housing. Also clean front of injection pump.
(3) Install new rubber o-ring into machined groove
(Fig. 14) at pump mounting area.
Fig. 14 FUEL INJECTION PUMP REMOVAL/INSTALLATION
1 - PUMP DRIVE GEAR NUT
2 - WASHER
3 - PUMP DRIVE GEAR
4 - RUBBER O-RING
5 - FUEL INJECTION PUMP6 - PUMP MOUNTING NUTS (3)
7 - PUMP MOUNTING STUDS (3)
8 - O-RING MACHINED GROOVE
9 - FRONT TIMING GEAR COVER
Fig. 13 DRIVE GEAR REMOVAL
1 - FRONT TIMING GEAR COVER
2 - GEAR PULLER TOOL
DRFUEL DELIVERY - DIESEL 14 - 67
FUEL INJECTION PUMP (Continued)