Ignition cylinder JEEP GRAND CHEROKEE 2003 WJ / 2.G User Guide

(3) Disconnect the instrument panel wire harness
connector from the SKIM connector.
(4) Remove the screw that secures the SKIM to
the bottom of the steering column housing (Fig. 16).
(5) Disengage the antenna ring of the SKIM from
around the ignition lock cylinder housing.
(6) Remove the SKIM from the steering column.
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Position the SKIM to the underside of the
steering column (Fig. 16).
(2) Engage the antenna ring of the SKIM around
the ignition lock cylinder housing.
(3) Install and tighten the screw that secures the
SKIM to the bottom of the steering column hous-
ing.Tighten the screw to 3.4 N´m (30 in lbs.).
(4) Reconnect the instrument panel wire harness
connector to the SKIM connector.(5) Reinstall the steering column opening cover
onto the instrument panel. (Refer to 23 - BODY/IN-
STRUMENT PANEL/STEERING COLUMN OPEN-
ING COVER - INSTALLATION).
(6) Reconnect the battery negative cable.
(7) Perform the SKIS Replacement procedure
using the DRBIIIt.
(8) Perform the SKIS Initialization Procedure
using the DRBIIIt.
TRANSMISSION CONTROL
MODULE
DESCRIPTION
The Transmission Control Module (TCM) is located
in the engine compartment on the right (passenger)
side and is mounted to the inner fender (Fig. 17).
OPERATION
The Transmission Control Module (TCM) controls
all electronic operations of the transmission. The
TCM receives information regarding vehicle opera-
tion from both direct and indirect inputs, and selects
the operational mode of the transmission. Direct
inputs are hardwired to, and used specifically by the
TCM. Indirect inputs originate from other compo-
nents/modules, and are shared with the TCM via the
vehicle communication bus.
Some examples ofdirect inputsto the TCM are:
²Battery (B+) voltage
²Ignition ªONº voltage
²Transmission Control Relay (Switched B+)
²Throttle Position Sensor
²Crankshaft Position Sensor
²Transmission Range Sensor
Fig. 16
Fig. 17 Transmission Control Module Location
1 - TRANSMISSION CONTROL MODULE (TCM)
2 - 60±WAY CONNECTOR
WJELECTRONIC CONTROL MODULES 8E - 19
SENTRY KEY IMMOBILIZER MODULE (Continued)

²a faulty or improperly adjusted switch that
allows a lamp to stay on. Refer to Ignition-Off Draw
Test in 8, Battery for more information.
INSPECTION
The Powertrain Control Module (PCM) monitors
critical input and output circuits of the charging sys-
tem, making sure they are operational. A Diagnostic
Trouble Code (DTC) is assigned to each input and
output circuit monitored by the On-Board Diagnostic
(OBD) system. Some charging system circuits are
checked continuously, and some are checked only
under certain conditions.
Refer to Diagnostic Trouble Codes in; Powertrain
Control Module; Electronic Control Modules for more
DTC information. This will include a complete list of
DTC's including DTC's for the charging system.
To perform a complete test of the charging system,
refer to the appropriate Powertrain Diagnostic Proce-
dures service manual and the DRBtscan tool. Per-
form the following inspections before attaching the
scan tool.(1) Inspect the battery condition. Refer to 8, Bat-
tery for procedures.
(2) Inspect condition of battery cable terminals,
battery posts, connections at engine block, starter
solenoid and relay. They should be clean and tight.
Repair as required.
(3) Inspect all fuses in both the fuseblock and
Power Distribution Center (PDC) for tightness in
receptacles. They should be properly installed and
tight. Repair or replace as required.
(4) Inspect generator mounting bolts for tightness.
Replace or tighten bolts if required. Refer to the Gen-
erator Removal/Installation section of this group for
torque specifications.
(5) Inspect generator drive belt condition and ten-
sion. Tighten or replace belt as required. Refer to
Belt Tension Specifications in 7, Cooling System.
(6) Inspect automatic belt tensioner (if equipped).
Refer to 7, Cooling System for information.
(7) Inspect generator electrical connections at gen-
erator field, battery output, and ground terminal (if
equipped). Also check generator ground wire connec-
tion at engine (if equipped). They should all be clean
and tight. Repair as required.
SPECIFICATIONS
GENERATOR RATINGS - GAS POWERED
TYPE PART NUMBER RATED SAE AMPS ENGINES MINIMUM TEST AMPS
BOSCH 56041322 136 4.0L 6-Cylinder 100
DENSO 56041324 136 4.7L V-8 100
TORQUE - GAS POWERED
DESCRIPTION N-m Ft. Lbs. In. Lbs.
Generator Mounting Bolts-4.0L 55 41
Generator Vertical Mounting Bolt-4.7L 40 29
Generator (long) Horizontal Mounting
Bolt-4.7L55 41
Generator (short) Horizontal Mounting
Bolt-4.7L55 41
Generator B+ Terminal Nut 11 95
WJCHARGING 8F - 25
CHARGING (Continued)

Starting System Diagnosis
CONDITION POSSIBLE CAUSE CORRECTION
STARTER FAILS TO
OPERATE.1. Battery discharged or
faulty.1. Refer to Battery in the Diagnosis and Testing section of
Group 8A - Battery. Charge or replace the battery, if
required.
2. Starting circuit wiring
faulty.2. Refer to Starting System in Group 8W - Wiring
Diagrams. Test and repair the starter feed and/or control
circuits, if required.
3. Starter relay faulty. 3. Refer to Starter Relay in the Diagnosis and Testing
section of this group. Replace the starter relay, if
required.
4. Ignition switch faulty. 4. Refer to Ignition Switch and Key Lock Cylinder in the
Diagnosis and Testing section of Group 8D - Ignition
System. Replace the ignition switch, if required.
5. Park/Neutral position
switch faulty or
misadjusted.5. Refer to Park/Neutral Position Switch in the Diagnosis
and Testing section of Group 21 - Transmission. Replace
the park/neutral position switch, if required.
6. Starter solenoid faulty. 6. Refer to Starter Motor in the Diagnosis and Testing
section of this group. Replace the starter motor assembly,
if required.
7. Starter motor faulty. 7. If all other starting system components and circuits test
OK, replace the starter motor assembly.
STARTER ENGAGES,
FAILS TO TURN
ENGINE.1. Battery discharged or
faulty.1. Refer to Battery in the Diagnosis and Testing section of
Group 8A - Battery. Charge or replace the battery, if
required.
2. Starting circuit wiring
faulty.2. Refer to Starting System in Group 8W - Wiring
Diagrams. Test and repair the starter feed and/or control
circuits, if required.
3. Starter motor faulty. 3. If all other starting system components and circuits test
OK, replace the starter motor assembly.
4. Engine seized. 4. Refer to Engine Diagnosis in the Diagnosis and Testing
section of Group 9 - Engine.
STARTER ENGAGES,
SPINS OUT BEFORE
ENGINE STARTS.1. Starter ring gear faulty. 1. Refer to Starter Motor in the Removal and Installation
section of this group. Remove the starter motor to inspect
the starter ring gear. Replace the starter ring gear, if
required.
2. Starter motor faulty. 2. If all other starting system components and circuits test
OK, replace the starter motor assembly.
STARTER DOES NOT
DISENGAGE.1. Starter motor
improperly installed.1. Refer to Starter Motor in the Removal and Installation
section of this group. Tighten the starter mounting
hardware to the correct tightness specifications.
2. Starter relay faulty. 2. Refer to Starter Relay in the Diagnosis and Testing
section of this group. Replace the starter relay, if
required.
3. Ignition switch faulty. 3. Refer to Ignition Switch and Key Lock Cylinder in the
Diagnosis and Testing section of Group 8D - Ignition
System. Replace the ignition switch, if required.
4. Starter motor faulty. 4. If all other starting system components and circuits test
OK, replace the starter motor assembly.
WJSTARTING 8F - 31
STARTING (Continued)

INSPECTION
For complete circuit diagrams, refer toStarting
Systemin the Contents of Group 8W - Wiring Dia-
grams. Before removing any unit from the starting
system for repair or diagnosis, perform the following
inspections:
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO GROUP 8M - PASSIVE
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING WHEEL, STEERING COLUMN, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
²Battery- Visually inspect the battery for indi-
cations of physical damage and loose or corroded
cable connections. Determine the state-of-charge and
cranking capacity of the battery. Charge or replace
the battery, if required. Refer toBatteryin the
proper section of Group 8A - Battery for complete ser-
vice information for the battery.
²Ignition Switch- Visually inspect the ignition
switch for indications of physical damage and loose
or corroded wire harness connections. Refer toIgni-
tion Switch and Key Lock Cylinderin the proper
section of Group 8D - Ignition System for complete
service information for the ignition switch.
²Park/Neutral Position Switch- Visually
inspect the park/neutral position switch for indica-
tions of physical damage and loose or corroded wire
harness connections. Refer toPark/Neutral Posi-
tion Switchin the proper section of Group 21 -
Transmission for complete service information for the
park/neutral position switch.
²Starter Relay- Visually inspect the starter
relay for indications of physical damage and loose or
corroded wire harness connections.
²Starter Motor- Visually inspect the starter
motor for indications of physical damage and loose or
corroded wire harness connections.
²Starter Solenoid- Visually inspect the starter
solenoid for indications of physical damage and loose
or corroded wire harness connections.
²Wiring- Visually inspect the wire harnesses for
damage. Repair or replace any faulty wiring, as
required. Refer to the proper section ofGroup 8W -
Wiring Diagramsfor complete service information
and circuit diagrams for the starting system wiring
components.TESTING
COLD CRANKING TEST
For complete circuit diagrams, refer toStarting
Systemin the Contents of Group 8W - Wiring Dia-
grams. The battery must be fully-charged and load-
tested before proceeding. Refer toBatteryin the
Diagnosis and Testing section of Group 8A - Battery
for the procedures.
(1) Connect a suitable volt-ampere tester to the
battery terminals (Fig. 1). See the instructions pro-
vided by the manufacturer of the volt-ampere tester
being used.
(2) Fully engage the parking brake.
(3) Place the automatic transmission gearshift
selector lever in the Park position.
(4) Verify that all lamps and accessories are
turned off.
(5) To prevent the engine from starting, remove
the Automatic ShutDown (ASD) relay. The ASD relay
is located in the Power Distribution Center (PDC), in
the engine compartment. Refer to the fuse and relay
layout label affixed to the underside of the PDC cover
for ASD relay identification and location.
(6) Rotate and hold the ignition switch in the Start
position. Note the cranking voltage and current
(amperage) draw readings shown on the volt-ampere
tester.
(a) If the voltage reads below 9.6 volts, refer to
Starter Motorin the Diagnosis and Testing sec-
tion of this group. If the starter motor is OK, refer
toEngine Diagnosisin the Diagnosis and Testing
section of Group 9 - Engine for further testing of
the engine. If the starter motor is not OK, replace
the faulty starter motor.
Fig. 1 Volts-Amps Tester Connections - Typical
1 - POSITIVE CLAMP
2 - NEGATIVE CLAMP
3 - INDUCTION AMMETER CLAMP
8F - 32 STARTINGWJ
STARTING (Continued)

Repeat the test. If the reading is still above 0.2 volt,
replace the faulty battery positive cable.
(4) Connect the voltmeter to measure between the
battery negative terminal post and a good clean
ground on the engine block (Fig. 5). Rotate and hold
the ignition switch in the Start position. Observe the
voltmeter. If the reading is above 0.2 volt, clean and
tighten the battery negative cable attachment on the
engine block. Repeat the test. If the reading is still
above 0.2 volt, replace the faulty battery negative
cable.(5) Connect the positive lead of the voltmeter to
the starter housing. Connect the negative lead of the
voltmeter to the battery negative terminal post (Fig.
6). Rotate and hold the ignition switch in the Start
position. Observe the voltmeter. If the reading is
above 0.2 volt, correct the poor starter to engine
block ground contact.
If the resistance tests detect no feed circuit prob-
lems, refer toStarter Motorin the Diagnosis and
Testing section of this group.
CONTROL CIRCUIT TESTING
The starter control circuit components should be
tested in the order in which they are listed, as fol-
lows:
²Starter Relay- Refer toStarter Relayin the
Diagnosis and Testing section of this group for the
procedures.
²Starter Solenoid- Refer toStarter Motorin
the Diagnosis and Testing section of this group for
the procedures.
²Ignition Switch- Refer toIgnition Switch
and Key Lock Cylinderin the Diagnosis and Test-
ing section of Group 8D - Ignition System for the pro-
cedures.
²Park/Neutral Position Switch- Refer to
Park/Neutral Position Switchin the Diagnosis
and Testing section of Group 21 - Transmission for
the procedures.
²Wire harnesses and connections- Refer to
Starting Systemin the Contents of Group 8W -
Wiring Diagrams for complete circuit diagrams.
Fig. 4 Test Battery Positive Cable Resistance -
Typical
1 - BATTERY
2 - VOLTMETER
3 - STARTER MOTOR
Fig. 5 Test Ground Circuit
1 - VOLTMETER
2 - BATTERY
3 - ENGINE GROUND
Fig. 6 Test Starter Ground - Typical
1 - STARTER MOTOR
2 - BATTERY
3 - VOLTMETER
8F - 34 STARTINGWJ
STARTING (Continued)

(1) Remove the starter relay from the PDC. Refer
toStarter Relayin the Removal and Installation
section of this group for the procedures.
(2) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 3. If not OK, replace the faulty relay.
(3) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75   5 ohms. If OK, go to Step
4. If not OK, replace the faulty relay.
(4) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, perform the Relay Circuit Test that
follows. If not OK, replace the faulty relay.
RELAY CIRCUIT TEST
(1) The relay common feed terminal cavity (30) is
connected to battery voltage and should be hot at all
times. If OK, go to Step 2. If not OK, repair the open
circuit to the fuse in the PDC as required.
(2) The relay normally closed terminal (87A) is
connected to terminal 30 in the de-energized position,
but is not used for this application. Go to Step 3.
(3) The relay normally open terminal (87) is con-
nected to the common feed terminal (30) in the ener-
gized position. This terminal supplies battery voltage
to the starter solenoid field coils. There should be
continuity between the cavity for relay terminal 87
and the starter solenoid terminal at all times. If OK,
go to Step 4. If not OK, repair the open circuit to the
starter solenoid as required.
(4) The coil battery terminal (86) is connected to
the electromagnet in the relay. It is energized when
the ignition switch is held in the Start position.
Check for battery voltage at the cavity for relay ter-
minal 86 with the ignition switch in the Start posi-tion, and no voltage when the ignition switch is
released to the On position. If OK, go to Step 5. If
not OK, check for an open or short circuit to the igni-
tion switch and repair, if required. If the circuit to
the ignition switch is OK, refer toIgnition Switch
and Key Lock Cylinderin the Diagnosis and Test-
ing section of Group 8D - Ignition System for testing
of the ignition switch.
(5) The coil ground terminal (85) is connected to
the electromagnet in the relay. It is grounded
through the park/neutral position switch only when
the gearshift selector lever is in the Park or Neutral
positions. Check for continuity to ground at the cav-
ity for relay terminal 85. If not OK, check for an
open or short circuit to the park/neutral position
switch and repair, if required. If the circuit to the
park/neutral position switch is OK, refer toPark/
Neutral Position Switchin the Diagnosis and
Testing section of Group 21 - Transmission for testing
of the park/neutral position switch.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cover from the Power Distribution
Center (PDC) (Fig. 14) .
Fig. 13 Starter Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
Fig. 14 Power Distribution Center
1 - RIGHT FENDER
2 - BATTERY
3 - POWER DISTRIBUTION CENTER
4 - COVER
WJSTARTING 8F - 39
STARTER MOTOR RELAY (Continued)

IGNITION CONTROL
TABLE OF CONTENTS
page page
IGNITION CONTROL
DESCRIPTION..........................1
OPERATION............................1
SPECIFICATIONS
ENGINE FIRING ORDER - 4.0L 6-CYLINDER
ENGINE..............................2
ENGINE FIRING ORDERÐ4.7L V-8 ENGINE . . 2
IGNITION COIL RESISTANCE - 4.0L ENGINE . 2
IGNITION COIL RESISTANCEÐ4.7L V-8
ENGINE..............................2
IGNITION TIMING......................2
SPARK PLUGS........................3
TORQUE - IGNITION SYSTEM............3
AUTO SHUT DOWN RELAY
DESCRIPTION - PCM OUTPUT.............3
OPERATION
OPERATION - PCM OUTPUT.............3
OPERATION - ASD SENSE - PCM INPUT....4
REMOVAL.............................4
INSTALLATION..........................4
CAMSHAFT POSITION SENSOR
DESCRIPTION
DESCRIPTION - 4.0L....................4
DESCRIPTION - 4.7L....................5
OPERATION
OPERATION - 4.0L.....................5
OPERATION - 4.7L.....................5
REMOVAL
REMOVAL - 4.0L.......................6
REMOVAL - 4.7L.......................7INSTALLATION
INSTALLATION - 4.0L...................8
INSTALLATION - 4.7L...................9
COIL RAIL
DESCRIPTION..........................9
OPERATION...........................10
REMOVAL.............................10
INSTALLATION.........................11
IGNITION COIL
DESCRIPTION.........................11
OPERATION...........................12
REMOVAL.............................12
INSTALLATION.........................12
IGNITION COIL CAPACITOR
DESCRIPTION.........................13
OPERATION...........................13
REMOVAL.............................13
INSTALLATION.........................13
KNOCK SENSOR
DESCRIPTION.........................13
OPERATION...........................13
REMOVAL.............................14
INSTALLATION.........................15
SPARK PLUG
DESCRIPTION.........................15
DIAGNOSIS AND TESTING - SPARK PLUG
CONDITIONS.........................15
REMOVAL.............................18
CLEANING............................18
INSTALLATION.........................18
IGNITION CONTROL
DESCRIPTION
Two different ignition systems are used. One type
of system is for the 4.0L 6±cylinder engine. The other
is for the 4.7L V-8 engine.
OPERATION
The 4.0L 6±cylinder engine uses a one-piece coil
rail containing three independent coils. Although cyl-
inder firing order is the same as 4.0L engines of pre-
vious years, spark plug firing is not. The 3 coils dual-
fire the spark plugs on cylinders 1±6, 2±5 and/or 3±4.
When one cylinder is being fired (on compressionstroke), the spark to the opposite cylinder is being
wasted (on exhaust stroke). The one-piece coil bolts
directly to the cylinder head. Rubber boots seal the
secondary terminal ends of the coils to the top of all
6 spark plugs. One electrical connector (located at
the rear end of the coil rail) is used for all three coils.
The 4.7L V-8 engine uses 8 dedicated and individ-
ually fired coil for each spark plug. Each coil is
mounted directly to the top of each spark plug. A sep-
arate electrical connector is used for each coil.
Because of coil design, spark plug cables (second-
ary cables) are not used on either engine. Adistrib-
utor is not usedwith either the 4.0L or 4.7L
engines.
WJIGNITION CONTROL 8I - 1

The ignition system is controlled by the powertrain
control module (PCM) on all engines.
The ignition system consists of:
²Spark Plugs
²Ignition Coil(s)
²Powertrain Control Module (PCM)
²Crankshaft Position Sensor
²Camshaft Position Sensor
²The MAP, TPS, IAC and ECT also have an effect
on the control of the ignition system.
SPECIFICATIONS
ENGINE FIRING ORDER - 4.0L 6-CYLINDER
ENGINEENGINE FIRING ORDERÐ4.7L V-8 ENGINE
IGNITION COIL RESISTANCE - 4.0L ENGINE
PRIMARY RESISTANCE 21-27ÉC (70-80ÉF)
0.71 - 0.88 Ohms
IGNITION COIL RESISTANCEÐ4.7L V-8
ENGINE
PRIMARY RESISTANCE
21-27ÉC (70-80ÉF)SECONDARY
RESISTANCE 21-27ÉC
(70-80ÉF)
0.6 - 0.9 Ohms 6,000 - 9,000 Ohms
IGNITION TIMING
All ignition timing functions are controlled by the
Powertrain Control Module (PCM). Mechanical
adjustments are not needed and can't be made.
On the 4.0L 6±cylinder engine, do not attempt to
rotate the oil pump drive to adjust timing. This
adjustment is used for fuel synchronization after
camshaft position sensor replacement.
8I - 2 IGNITION CONTROLWJ
IGNITION CONTROL (Continued)

The ASD relay will be shut±down, meaning the
12±volt power supply to the ASD relay will be de-ac-
tivated by the PCM if:
²the ignition key is left in the ON position. This
is if the engine has not been running for approxi-
mately 1.8 seconds.
²there is a crankshaft position sensor signal to
the PCM that is lower than pre-determined values.
OPERATION - ASD SENSE - PCM INPUT
A 12 volt signal at this input indicates to the PCM
that the ASD has been activated. The relay is used to
connect the oxygen sensor heater element, ignition
coil and fuel injectors to 12 volt + power supply.
This input is used only to sense that the ASD relay
is energized. If the Powertrain Control Module
(PCM) does not see 12 volts at this input when the
ASD should be activated, it will set a Diagnostic
Trouble Code (DTC).
REMOVAL
The ASD relay is located in the Power Distribution
Center (PDC) (Fig. 1). 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 ASD relay is located in the Power Distribution
Center (PDC) (Fig. 1). Refer to label on PDC cover
for relay location.
(1) Install relay to PDC.
(2) Install cover to PDC.
CAMSHAFT POSITION
SENSOR
DESCRIPTION
DESCRIPTION - 4.0L
The Camshaft Position Sensor (CMP) on the 4.0L
6±cylinder engine is bolted to the top of the oil pump
drive shaft assembly (Fig. 2). The sensor and drive
shaft assembly is located on the right side of the
engine near the oil filter (Fig. 3).
Fig. 1 Power Distribution Center (PDC) Location
1 - PCM
2 - COOLANT TANK
Fig. 2 CMP and Oil Pump Drive ShaftÐ4.0L Engine
1 - CAMSHAFT POSITION SENSOR
2 - MOUNTING BOLTS (2)
3 - PULSE RING
4 - DRIVE GEAR (TO CAMSHAFT)
5 - OIL PUMP DRIVESHAFT
6 - SENSOR BASE (OIL PUMP DRIVESHAFT ASSEMBLY)
8I - 4 IGNITION CONTROLWJ
AUTO SHUT DOWN RELAY (Continued)

DESCRIPTION - 4.7L
The Camshaft Position Sensor (CMP) on the 4.7L
V±8 engine is bolted to the front/top of the right cyl-
inder head (Fig. 4).
OPERATION
OPERATION - 4.0L
The CMP sensor contains a hall effect device called
a sync signal generator to generate a fuel sync sig-
nal. This sync signal generator detects a rotating
pulse ring (shutter) on the oil pump drive shaft (Fig.
2). The pulse ring rotates 180 degrees through the
sync signal generator. Its signal is used in conjunc-
tion with the crankshaft position sensor to differenti-
ate between fuel injection and spark events. It is also
used to synchronize the fuel injectors with their
respective cylinders.
When the leading edge of the pulse ring (shutter)
enters the sync signal generator, the following occurs:
The interruption of magnetic field causes the voltage
to switch high resulting in a sync signal of approxi-
mately 5 volts.When the trailing edge of the pulse ring (shutter)
leaves the sync signal generator, the following occurs:
The change of the magnetic field causes the sync sig-
nal voltage to switch low to 0 volts.
OPERATION - 4.7L
The CMP sensor contains a hall effect device called
a sync signal generator to generate a fuel sync sig-
nal. This sync signal generator detects notches
located on a tonewheel. The tonewheel is located at
the front of the camshaft for the right cylinder head
(Fig. 5). As the tonewheel rotates, the notches pass
through the sync signal generator. The pattern of the
notches (viewed counter-clockwise from front of
engine) is: 1 notch, 2 notches, 3 notches, 3 notches, 2
notches 1 notch, 3 notches and 1 notch. The signal
from the CMP sensor is used in conjunction with the
crankshaft position sensor to differentiate between
fuel injection and spark events. It is also used to syn-
chronize the fuel injectors with their respective cylin-
ders.
Fig. 3 CMP LocationÐ4.0L Engine
1 - OIL FILTER
2 - CAMSHAFT POSITION SENSOR
3 - CLAMP BOLT
4 - HOLD-DOWN CLAMP
5 - MOUNTING BOLTS (2)
6 - ELEC. CONNECTORFig. 4 CMP LocationÐ4.7L Engine
1 - RIGHT CYLINDER HEAD
2 - CAMSHAFT POSITION SENSOR
3 - MOUNTING BOLT
4 - ELEC. CONNECTOR
WJIGNITION CONTROL 8I - 5
CAMSHAFT POSITION SENSOR (Continued)