2003 DODGE RAM engine

The sensor is a hall effect device combined with an
internal magnet. It is also sensitive to steel within a
certain distance from it.
On 5.9L V-8 engines, the flywheel/drive plate has 8
single notches, spaced every 45 degrees, at its outer
edge (Fig. 8).
The notches cause a pulse to be generated when
they pass under the sensor. The pulses are the input
to the PCM. For each engine revolution, there are 8
pulses generated on V-8 engines.
The engine will not operate if the PCM does not
receive a CKP sensor input.
8.0L V-10
The Crankshaft Position (CKP) sensor detects
notches machined into the middle of the crankshaft
(Fig. 9).
There are five sets of notches. Each set contains
two notches. Basic ignition timing is determined by
the position of the last notch in each set of notches.
Once the Powertrain Control Module (PCM) senses
the last notch, it will determine crankshaft position
(which piston will next be at Top Dead Center). An
input from the camshaft position sensor is also
needed. It may take the module up to one complete
engine revolution to determine crankshaft position
during engine cranking.The PCM uses the signal from the camshaft posi-
tion sensor to determine fuel injector sequence. Once
crankshaft position has been determined, the PCM
begins energizing a ground circuit to each fuel injec-
tor to provide injector operation.
Fig. 7 CKP SENSOR OPERATION AND NOTCHES -
5.7L V-8
1 - RIGHT / REAR SIDE OF CYLINDER BLOCK
2 - MACHINED HOLE
3 - NOTCHES
Fig. 8 CKP SENSOR OPERATION ± 5.9L V-8
1 - CRANKSHAFT POSITION SENSOR
2 - NOTCHES
3 - FLYWHEEL
Fig. 9 CKP SENSOR OPERATION ± 8.0L V-10
ENGINE
1 - CRANKSHAFT NOTCHES
2 - CRANKSHAFT
3 - CRANKSHAFT POSITION SENSOR
14 - 28 FUEL INJECTION - GASDR
CRANKSHAFT POSITION SENSOR (Continued)

REMOVAL
3.7L V-6
The Crankshaft Position (CKP) sensor is mounted
into the right rear side of the cylinder block (Fig. 10).
It is positioned and bolted into a machined hole.
(1) Raise vehicle.
(2) Disconnect sensor electrical connector.
(3) Remove sensor mounting bolt (Fig. 10).
(4) Carefully twist sensor from cylinder block.
(5) Check condition of sensor o-ring.
4.7L V-8
The Crankshaft Position (CKP) sensor is located at
the right-rear side of the engine cylinder block (Fig.
11). It is positioned and bolted into a machined hole
in the engine block.
(1) Raise vehicle.(2) Disconnect CKP electrical connector at sensor.
(3) Remove CKP mounting bolt (Fig. 11).
(4) Carefully twist sensor from cylinder block.
(5) Remove sensor from vehicle.
(6) Check condition of sensor o-ring.
5.7L V-8
The Crankshaft Position (CKP) sensor is located at
the right-rear side of the engine cylinder block (Fig.
12). It is positioned and bolted into a machined hole
in the engine block.
(1) Raise vehicle.
(2) Disconnect CKP electrical connector at sensor
(Fig. 12).
(3) Remove CKP mounting bolt (Fig. 12).
(4) Carefully twist sensor from cylinder block.
(5) Remove sensor from vehicle.
(6) Check condition of sensor o-ring.
Fig. 10 CKP REMOVAL / INSTALLATION - 3.7L
1 - MOUNTING BOLT
2 - CKP SENSOR
3 - O-RING
Fig. 11 CKP REMOVAL / INSTALLATION - 4.7L
1 - CRANKSHAFT POSITION SENSOR
2 - MOUNTING BOLT
DRFUEL INJECTION - GAS 14 - 29
CRANKSHAFT POSITION SENSOR (Continued)

5.9L Gas
The sensor is bolted to the top of the cylinder block
near the rear of right cylinder head (Fig. 13).
(1) Raise vehicle.(2) Disconnect crankshaft position sensor pigtail
harness from main wiring harness.
(3) Remove two sensor (recessed hex head) mount-
ing bolts (Fig. 13).
(4) Remove sensor from engine.
8.0L V±10
The crankshaft position sensor is located on the
right-lower side of the cylinder block, forward of the
right engine mount, just above the oil pan rail (Fig.
14).
(1) Raise and support vehicle.
(2) Disconnect sensor pigtail harness from main
engine wiring harness.
(3) Remove sensor mounting bolt (Fig. 15).
(4) Cut plastic tie strap (Fig. 14) securing sensor
pigtail harness to side of engine block.
(5) Carefully pry sensor from cylinder block in a
rocking action with two small screwdrivers.
(6) Remove sensor from vehicle.
(7) Check condition of sensor o-ring (Fig. 16).
INSTALLATION
3.7L V-6
(1) Clean out machined hole in engine block.
(2) Apply a small amount of engine oil to sensor
o-ring.
(3) Install sensor into engine block with a slight
rocking and twisting action.
Fig. 12 CKP REMOVAL / INSTALLATION - 5.7L V-8
1 - CYLINDER BLOCK - RIGHT / REAR
2 - ELEC. CONNECTOR
3 - MOUNTING BOLT
4 - CKP SENSOR
Fig. 13 CKP REMOVAL / INSTALLATION - 5.9L V-8
1 - GROMMET
2 - MOUNTING BOLTS (2)
3 - CRANKSHAFT POSITION SENSOR
4 - RIGHT EXHAUST MANIFOLD
5 - TRANSMISSION BELL HOUSING
Fig. 14 CKP SENSOR LOCATION ± 8.0L V-10
1 - CRANKSHAFT POSITION SENSOR
2 - HOLE
3 - OIL FILTER
4 - PLASTIC TIE STRAP
5 - PIGTAIL HARNESS
14 - 30 FUEL INJECTION - GASDR
CRANKSHAFT POSITION SENSOR (Continued)

CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to cylinder
block. If sensor is not flush, damage to sensor
mounting tang may result.
(4) Install mounting bolt and tighten to 28 N´m
(21 ft. lbs.) torque.
(5) Connect electrical connector to sensor.
(6) Lower vehicle.
4.7L V-8
(1) Clean out machined hole in engine block.
(2) Apply a small amount of engine oil to sensor
o-ring.
(3) Install sensor into engine block with a slight
rocking and twisting action.CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to cylinder
block. If sensor is not flush, damage to sensor
mounting tang may result.
(4) Install mounting bolt and tighten to 28 N´m
(21 ft. lbs.) torque.
(5) Connect electrical connector to sensor.
(6) Lower vehicle.
5.7L V-8
(1) Clean out machined hole in engine block.
(2) Apply a small amount of engine oil to sensor
o-ring.
(3) Install sensor into engine block with a slight
rocking and twisting action.
CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to cylinder
block. If sensor is not flush, damage to sensor
mounting tang may result.
(4) Install mounting bolt and tighten to 28 N´m
(21 ft. lbs.) torque.
(5) Connect electrical connector to sensor.
(6) Lower vehicle.
5.9L V-8 Gas
(1) Position crankshaft position sensor to engine.
(2) Install mounting bolts and tighten to 8 N´m (70
in. lbs.) torque.
(3) Connect main harness electrical connector to
sensor.
(4) Lower vehicle.
8.0L V-10
(1) Apply a small amount of engine oil to sensor
o-ring.
(2) Install sensor into cylinder block with a slight
rocking action. Do not twist sensor into position as
damage to o-ring may result.
CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to cylinder
block. If sensor is not flush, damage to sensor
mounting tang may result.
(3) Install mounting bolt and tighten to 8 N´m (70
in. lbs.) torque.
(4) Connect sensor pigtail harness to main engine
wiring harness
(5) Install new plastic tie strap (Fig. 14) to secure
sensor pigtail harness to side of engine block. Thread
tie strap through casting hole on cylinder block.
Fig. 15 CKP SENSOR R/I ± 8.0L V-10
1 - CRANKSHAFT POSITION SENSOR
2 - MOUNTING BOLT
3 - SENSOR POSITIONED FLUSH TO CYLINDER BLOCK
Fig. 16 SENSOR O-RING ± 8.0L V-10
1 - CRANKSHAFT POSITION SENSOR O-RING
2 - ELECTRICAL CONNECTOR
3 - PIGTAIL HARNESS
DRFUEL INJECTION - GAS 14 - 31
CRANKSHAFT POSITION SENSOR (Continued)

FUEL INJECTOR
DESCRIPTION
An individual fuel injector (Fig. 17) is used for each
individual cylinder.
OPERATION
OPERATION - FUEL INJECTOR
The top (fuel entry) end of the injector (Fig. 17) is
attached into an opening on the fuel rail.
The fuel injectors are electrical solenoids. The
injector contains a pintle that closes off an orifice at
the nozzle end. When electric current is supplied to
the injector, the armature and needle move a short
distance against a spring, allowing fuel to flow out
the orifice. Because the fuel is under high pressure, a
fine spray is developed in the shape of a pencil
stream. The spraying action atomizes the fuel, add-
ing it to the air entering the combustion chamber.
The nozzle (outlet) ends of the injectors are posi-
tioned into openings in the intake manifold just above
the intake valve ports of the cylinder head. The engine
wiring harness connector for each fuel injector is
equipped with an attached numerical tag (INJ 1, INJ
2 etc.). This is used to identify each fuel injector.
The injectors are energized individually in a sequen-
tial order by the Powertrain Control Module (PCM).
The PCM will adjust injector pulse width by switching
the ground path to each individual injector on and off.
Injector pulse width is the period of time that the
injector is energized. The PCM will adjust injector
pulse width based on various inputs it receives.
Battery voltage is supplied to the injectors through
the ASD relay.
The PCM determines injector pulse width based on
various inputs.
OPERATION - PCM OUTPUT
The nozzle ends of the injectors are positioned into
openings in the intake manifold just above the intake
valve ports of the cylinder head. The engine wiring
harness connector for each fuel injector is equipped
with an attached numerical tag (INJ 1, INJ 2 etc.).
This is used to identify each fuel injector with its
respective cylinder number.
The injectors are energized individually in a sequen-
tial order by the Powertrain Control Module (PCM).
The PCM will adjust injector pulse width by switching
the ground path to each individual injector on and off.
Injector pulse width is the period of time that the
injector is energized. The PCM will adjust injector
pulse width based on various inputs it receives.
Battery voltage (12 volts +) is supplied to the injec-
tors through the ASD relay. The ASD relay will shut-
down the 12 volt power source to the fuel injectors if
the PCM senses the ignition is on, but the engine is
not running. This occurs after the engine has not
been running for approximately 1.8 seconds.
The PCM determines injector on-time (pulse width)
based on various inputs.
REMOVAL
(1) Remove fuel rail. Refer to Fuel Injector Rail
Removal.
(2) Disconnect clip(s) that retain fuel injector(s) to
fuel rail (Fig. 18).
Fig. 17 FUEL INJECTOR
1 - FUEL INJECTOR
2 - NOZZLE
3 - TOP (FUEL ENTRY)
Fig. 18 INJECTOR RETAINING CLIP
1 - PLIERS
2 - INJECTOR CLIP
3 - FUEL INJECTOR - TYPICAL
4 - FUEL RAIL - TYPICAL
14 - 32 FUEL INJECTION - GASDR

INSTALLATION
(1) Install fuel injector(s) into fuel rail assembly
and install retaining clip(s).
(2) If same injector(s) is being reinstalled, install
new o-ring(s).
(3) Apply a small amount of clean engine oil to
each injector o-ring. This will aid in installation.
(4) Install fuel rail. Refer to Fuel Rail Installation.
(5) Start engine and check for fuel leaks.
FUEL PUMP RELAY
DESCRIPTION
The 5±pin, 12±volt, fuel pump relay is located in
the Power Distribution Center (PDC). Refer to the
label on the PDC cover for relay location.
OPERATION
The Powertrain Control Module (PCM) energizes
the electric fuel pump through the fuel pump relay.
The fuel pump relay is energized by first applying
battery voltage to it when the ignition key is turned
ON, and then applying a ground signal to the relay
from the PCM.
Whenever the ignition key is turned ON, the elec-
tric fuel pump will operate. But, the PCM will shut-
down the ground circuit to the fuel pump relay in
approximately 1±3 seconds unless the engine is oper-
ating or the starter motor is engaged.
REMOVAL
The fuel pump relay is located in the Power Distri-
bution Center (PDC) (Fig. 19). Refer to label on 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 pump relay is located in the Power Distri-
bution Center (PDC). Refer to label on PDC cover for
relay location.
(1) Install relay to PDC.
(2) Install cover to PDC.
IDLE AIR CONTROL MOTOR
DESCRIPTION
A separate IAC motor is not used with the 5.7L V-8
engine.
The IAC stepper motor is mounted to the throttle
body, and regulates the amount of air bypassing the
control of the throttle plate. As engine loads and
ambient temperatures change, engine rpm changes.
A pintle on the IAC stepper motor protrudes into a
passage in the throttle body, controlling air flow
through the passage. The IAC is controlled by the
Powertrain Control Module (PCM) to maintain the
target engine idle speed.
OPERATION
A separate IAC motor is not used with the 5.7L V-8
engine.
At idle, engine speed can be increased by retract-
ing the IAC motor pintle and allowing more air to
pass through the port, or it can be decreased by
restricting the passage with the pintle and diminish-
ing the amount of air bypassing the throttle plate.
The IAC is called a stepper motor because it is
moved (rotated) in steps, or increments. Opening the
IAC opens an air passage around the throttle blade
which increases RPM.
The PCM uses the IAC motor to control idle speed
(along with timing) and to reach a desired MAP dur-
ing decel (keep engine from stalling).
Fig. 19 PDC LOCATION
1 - BATTERY
2 - PDC (POWER DISTRIBUTION CENTER)
DRFUEL INJECTION - GAS 14 - 33
FUEL INJECTOR (Continued)

The IAC motor has 4 wires with 4 circuits. Two of
the wires are for 12 volts and ground to supply elec-
trical current to the motor windings to operate the
stepper motor in one direction. The other 2 wires are
also for 12 volts and ground to supply electrical cur-
rent to operate the stepper motor in the opposite
direction.
To make the IAC go in the opposite direction, the
PCM just reverses polarity on both windings. If only
1 wire is open, the IAC can only be moved 1 step
(increment) in either direction. To keep the IAC
motor in position when no movement is needed, the
PCM will energize both windings at the same time.
This locks the IAC motor in place.
In the IAC motor system, the PCM will count
every step that the motor is moved. This allows the
PCM to determine the motor pintle position. If the
memory is cleared, the PCM no longer knows the
position of the pintle. So at the first key ON, the
PCM drives the IAC motor closed, regardless of
where it was before. This zeros the counter. From
this point the PCM will back out the IAC motor and
keep track of its position again.
When engine rpm is above idle speed, the IAC is
used for the following:
²Off-idle dashpot (throttle blade will close quickly
but idle speed will not stop quickly)
²Deceleration air flow control
²A/C compressor load control (also opens the pas-
sage slightly before the compressor is engaged so
that the engine rpm does not dip down when the
compressor engages)
²Power steering load control
The PCM can control polarity of the circuit to con-
trol direction of the stepper motor.
IAC Stepper Motor Program:The PCM is also
equipped with a memory program that records the
number of steps the IAC stepper motor most recently
advanced to during a certain set of parameters. For
example: The PCM was attempting to maintain a
1000 rpm target during a cold start-up cycle. The last
recorded number of steps for that may have been
125. That value would be recorded in the memory
cell so that the next time the PCM recognizes the
identical conditions, the PCM recalls that 125 steps
were required to maintain the target. This program
allows for greater customer satisfaction due to
greater control of engine idle.
Another function of the memory program, which
occurs when the power steering switch (if equipped),
or the A/C request circuit, requires that the IAC step-
per motor control engine rpm, is the recording of the
last targeted steps into the memory cell. The PCM
can anticipate A/C compressor loads. This is accom-
plished by delaying compressor operation for approx-
imately 0.5 seconds until the PCM moves the IACstepper motor to the recorded steps that were loaded
into the memory cell. Using this program helps elim-
inate idle-quality changes as loads change. Finally,
the PCM incorporates a9No-Load9engine speed lim-
iter of approximately 1800 - 2000 rpm, when it rec-
ognizes that the TPS is indicating an idle signal and
IAC motor cannot maintain engine idle.
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the IAC motor through the PCM.
REMOVAL
3.7L V-6
The Idle Air Control (IAC) motor is located on the
side of the throttle body (Fig. 20).
(1) Remove air resonator box at throttle body.
(2) Disconnect electrical connector from IAC motor.
(3) Remove two mounting bolts (screws).
(4) Remove IAC motor from throttle body.
4.7L V-8
The Idle Air Control (IAC) motor is located on the
side of the throttle body (Fig. 21).
(1) Remove air resonator box at throttle body.
(2) Disconnect electrical connector from IAC motor.
(3) Remove two mounting bolts (screws).
(4) Remove IAC motor from throttle body.
Fig. 20 IDLE AIR CONTROL MOTOR - 3.7L V-6
1 - THROTTLE POSITION SENSOR (TPS)
2 - MOUNTING SCREWS
3 - IDLE AIR CONTROL MOTOR (IAC)
4 - MOUNTING SCREWS
14 - 34 FUEL INJECTION - GASDR
IDLE AIR CONTROL MOTOR (Continued)

5.7L V-8
The IAC motor is not serviceable on the 5.7L V-8
engine.
5.9L V-8
The IAC motor is located on the back of the throt-
tle body (Fig. 22).
(1) Remove air resonator box at throttle body.
(2) Disconnect electrical connector from IAC motor.
(3) Remove two mounting bolts (screws) (Fig. 22).
(4) Remove IAC motor from throttle body.
8.0L V-10
The IAC motor is located on the back of the throt-
tle body (Fig. 23).
(1) Remove the air cleaner cover.
(2) Remove the 4 air cleaner housing mounting
nuts and remove housing from throttle body.
(3) Disconnect electrical connector from IAC motor.
(4) Remove two mounting bolts (screw).
(5) Remove IAC motor from throttle body.
INSTALLATION
3.7L V-6
The Idle Air Control (IAC) motor is located on the
side of the throttle body (Fig. 20).
(1) Install IAC motor to throttle body.
(2) Install and tighten two mounting bolts (screws)
to 7 N´m (60 in. lbs.) torque.
(3) Install electrical connector.
(4) Install air resonator to throttle body.
4.7L V-8
The Idle Air Control (IAC) motor is located on the
side of the throttle body (Fig. 21).
(1) Install IAC motor to throttle body.
Fig. 21 IDLE AIR CONTROL MOTOR - 4.7L V-8
1 - THROTTLE BODY
2 - TPS
3 - IAC MOTOR
4 - IAT SENSOR
5 - MOUNTING SCREWS
Fig. 22 IDLE AIR CONTROL MOTOR - 5.9L V-8
1 - MOUNTING SCREWS
2 - IDLE AIR CONTROL MOTOR
Fig. 23 IAC MOTOR - 8.0L V-10
1 - IDLE AIR CONTROL MOTOR
2 - INTAKE MANIFOLD (UPPER HALF)
3 - THROTTLE POSITION SENSOR
4 - THROTTLE BODY
DRFUEL INJECTION - GAS 14 - 35
IDLE AIR CONTROL MOTOR (Continued)