All engines use resistor spark plugs. They have
resistance values ranging from 6,000 to 20,000 ohms
when checked with at least a 1000 volt spark plug
tester.
Do not use an ohm meter to check the resis-
tance of the spark plugs. This will give an inac-
curate reading.
Remove the spark plugs and examine them for
burned electrodes and fouled, cracked or broken por-
celain insulators. Keep plugs arranged in the order
in which they were removed from the engine. An iso-
lated plug displaying an abnormal condition indicates
that a problem exists in the corresponding cylinder.
Replace spark plugs at the intervals recommended in
Group O - Lubrication and Maintenance.
Spark plugs that have low mileage may be cleaned
and reused if not otherwise defective, carbon or oil
fouled. Refer to the Spark Plug Condition section of
this group.
The spark plugs are double platinum and have a
recommended service life of 100,000 miles for normal
driving conditions per schedule A in this manual. The
spark plugs have a recommended service life of
75,000 miles for serve driving conditions per schedule
B in this manual. A thin platinum pad is welded to
both electrode ends as show in (Fig. 3). Extreme care
must be used to prevent spark plug cross threading,
mis-gaping and ceramic insulator damage during
plug removal and installation.
CAUTION: Never attempt to file the electrodes or
use a wire brush for cleaning platinum plugs. This
would damage the platinum pads which would
shorten spark plug life.
Apply a very small amount of anti-seize compound
to the threads when reinstalling the vehicle's original
spark plugs that have been determined good.Do not
apply anti-seize compound to new spark plugs.
NOTE: Anti-seize compound is electrically conduc-
tive and can cause engine misfires if not applied
correctly. It is extremely important that the anti-
seize compound doesn't make contact with the
spark plug electrodes or ceramic insulator.
Never force a gap gauge between the platinum
electrodes or adjust the gap on platinum spark plugs
without reading the 3.3/3.8L Spark Plug Gap Mea-
surement procedures in this section.
Always tighten spark plugs to the specified torque.
Over tightening can cause distortion resulting in a
change in the spark plug gap. Overtightening can
also damage the cylinder head. Tighten spark plugs
to 28 N´m (20 ft. lbs.) torque.
Due to the engine packaging environment for the
3.3/3.8L engines, extreme care should be used wheninstalling the spark plugs to avoid cross threading
problems.
3.3/3.8L SPARK PLUG GAP MEASUREMENT
CAUTION: The Platinum pads can be damaged dur-
ing the measurement of checking the gap if extreme
care is not used.
²USE ONLY A TAPER GAP GAUGE (Fig. 2)
²Never force the gap gauge through the platinum
pads. Only apply enough force until resistance is felt.
²Never use a wire brush or spark plug cleaner
machine to clean platinum spark plugs
²Use an OSHA approved air nozzle when drying
gas fouled spark plugs.
If gap adjustment is required of platinum plug,
bend only the ground electrode. DO NOT TOUCH
the platinum pads. Use only a proper gapping tool
and check with a taper gap gauge.
CAUTION: Cleaning of the platinum plug may dam-
age the platinum tip.
SPARK PLUG CABLE
Spark Plug cables are sometimes referred to as
secondary ignition wires. The wires transfer electri-
cal current from the ignition coil pack, distributor
(3.0L), to individual spark plugs at each cylinder. The
resistive spark plug cables are of nonmetallic con-
struction. The cables provide suppression of radio fre-
quency emissions from the ignition system.
Check the spark plug cable connections for good
contact at the coil, distributor cap towers (3.0L), and
spark plugs. Terminals should be fully seated. The
insulators should be in good condition and should fit
tightly on the coil, distributor (3.0L) and spark plugs.
Spark plug cables with insulators that are cracked or
torn must be replaced.
Fig. 3 Platinum Pads
NSIGNITION SYSTEM 8D - 3
GENERAL INFORMATION (Continued)
Clean Spark Plug cables with a cloth moistened
with a non-flammable solvent. Wipe the cables dry.
Check for brittle or cracked insulation.
SPARK PLUG CABLESÐ3.3/3.8L
The spark plug cables and spark plug boots are
made from high temperature silicone materials. The
spark plug boots utilize metal heat shields for ther-
mal protection from the exhaust manifold. The heat
shields slide over the spark plug boots. The notches
on the heat shields ensure the spark plug boot and
shield twist together during spark plug boot removal.
They also identify proper heat shield installation on
the boot for service.Refer to 3.3/3.8L Spark Plug
Cable removal and installation.All spark plug
cable leads are properly identified with cylinder num-
bers. The inside of the spark plug boot is coated with
a special high temperature silicone grease for greater
sealing and to minimize boot bonding to the spark
plug insulator. The convoluted tubing on the rear
plug cables are made of a high temperature plastic
material. Under normal driving conditions, the spark
plug cables have a recommended service life of a
100,000 miles. The spark plugs have a recommended
service life of 75,000 miles for severe driving condi-
tions per schedule B in this manual.
The spark plug heat shield can be reused if an
ignition cable is replaced due to failure. Never reuse
heat shield's that have heat shield anti-twist, side or
spark plug attachment tabs bent or missing. Ensure
that the heat shield is properly attached to the spark
plug to avoid RFI problems. The bottom of the spark
plug heat shield must make contact with the spark
plug hex.
The front ignition cables must not make contact
with the oil dip stick tube and #5 cable must not
touch the coil mounting bolt to avoid abrasion/dielec-
tric failures.
IGNITION COIL
WARNING: THE DIRECT IGNITION SYSTEM GEN-
ERATES APPROXIMATELY 40,000 VOLTS. PER-
SONAL INJURY COULD RESULT FROM CONTACT
WITH THIS SYSTEM.
The ignition coil assembly consists of 3 indepen-
dent coils molded together (Fig. 4). The coil assembly
is mounted on the intake manifold. Spark plug cables
route to each cylinder from the coil. The coil fires two
spark plugs every power stroke. One plug is the cyl-
inder under compression, the other cylinder fires on
the exhaust stroke. The Powertrain Control Module
(PCM) determines which of the coils to charge and
fire at the correct time.
Coil 1 fires cylinders 1 and 4, coil 2 fires cylinders
2 and 5, coil 3 fires cylinders 3 and 6.The Auto Shutdown (ASD) relay provides battery
voltage to the ignition coil. The PCM provides a
ground contact (circuit) for energizing the coil. When
the PCM breaks the contact, the energy in the coil
primary transfers to the secondary causing the
spark. The PCM will de-energize the ASD relay if it
does not receive the crankshaft position sensor and
camshaft position sensor inputs. Refer to Auto Shut-
down (ASD) RelayÐPCM Output, in this section for
relay operation.
AUTOMATIC SHUTDOWN (ASD) RELAY
The Powertrain Control Module (PCM) operates
the Auto Shutdown (ASD) relay by switching the
ground path on and off.
The ASD relay supplies battery voltage to the fuel
injectors, electronic ignition coil and the heating ele-
ments in the oxygen sensors.
The PCM controls the relay by switching the
ground path for the solenoid side of the relay on and
off. The PCM turns the ground path off when the
ignition switch is in the Off position unless the 02
Heater Monitor test is being run. Refer to Group 25,
On-Board Diagnostics. When the ignition switch is in
the On or Crank position, the PCM monitors the
crankshaft position sensor and camshaft position sen-
sor signals to determine engine speed and ignition
timing (coil dwell). If the PCM does not receive the
crankshaft position sensor and camshaft position sen-
sor signals when the ignition switch is in the Run
position, it will de-energize the ASD relay.
The ASD relay is located in the Power Distribution
Center (PDC). The PDC is located on the driver's
side inner fender well (Fig. 5). A label on the under-
side of the PDC cover identifies the relays and fuses
in the PDC.
Fig. 4 Ignition Coil Pack
8D - 4 IGNITION SYSTEMNS
GENERAL INFORMATION (Continued)
NOTE: Over or under tightening effects knock sen-
sor performance, possibly causing improper spark
control.
DIAGNOSIS AND TESTING
TESTING FOR SPARK AT COILÐ2.4/3.3/3.8L
ENGINES
WARNING: THE DIRECT IGNITION SYSTEMS GEN-
ERATES APPROXIMATELY 40,000 VOLTS. PER-
SONAL INJURY COULD RESULT FROM CONTACT
WITH THIS SYSTEM.
The coil pack contains independent coils. Each coil
must be checked individually.
CAUTION: Spark plug wire damage may occur if
the spark plug is moved more than 1/4 inch away
from the engine ground.
CAUTION: Do not leave any one spark plug cable
disconnected any longer than 30 seconds or possi-
ble heat damage to catalytic converter will occur.
CAUTION: Test must be performed at idle and in
park only with the parking brake on.
Use a new spark plug and spark plug cable
for the following test.
(1) Insert a new spark plug into the new spark
plug boot. Ground the plug to the engine (Fig. 15).
Do not hold with your hand.
(2) Starting with coil insulator #1, remove it from
the DIS coil.(3) Plug the test spark plug cable onto #1 coil
tower. Make sure a good connection is made; there
should be a click sound.
(4) Crank the engine and look for spark across the
electrodes of the spark plug.
CAUTION: Always install the cable back on the coil
tower after testing to avoid damage to the coil and
catalytic converter.
(5) Repeat the above test for the remaining coils. If
there is no spark during all cylinder tests, proceed to
the Failure To Start Test.
(6) If one or more tests indicate irregular, weak, or
no spark, proceed to Check Coil Test.
TESTING FOR SPARK AT COILÐ3.0L
WARNING: APPLY PARKING BRAKE AND/OR
BLOCK THE WHEELS BEFORE PERFORMING ANY
TEST WITH THE ENGINE RUNNING.
CAUTION: Spark plug cables may be damaged if
this test is performed with more than 1/4 inch clear-
ance between the cable and engine ground.
Remove the coil secondary cable from the distribu-
tor cap. Hold the end of cable about 6 mm (1/4-inch)
away from a good engine ground using non-conduc-
tive ignition pliers (Fig. 16). Crank the engine and
inspect for spark at the coil secondary cable.
There must be a constant spark at the coil second-
ary cable. If spark is not constant or there is no
spark, proceed to the failure to start test. If the
spark is constant, continue to crank engine and,
while slowly moving coil secondary cable away from
ground, look for arcing at the coil tower. If arcing
occurs at the tower, replace the coil.
If a constant spark is present and no arcing occurs
at the coil tower, the ignition system is producing the
necessary high secondary voltage. However, make
Fig. 15 Testing For Spark
Fig. 16 Checking for Spark
8D - 8 IGNITION SYSTEMNS
GENERAL INFORMATION (Continued)
sure that the spark plugs are firing. Inspect the dis-
tributor rotor, cap, spark plug cables, and spark
plugs. If they are in proper working order, the igni-
tion system is not the reason why the engine will not
start. Inspect the fuel system and engine for proper
operation.
CHECK COIL TESTÐ2.4L
Coil one fires cylinders 1 and 4, coil two fires
cylinders 2 and 3. Each coil tower is labeled
with the number of the corresponding cylinder.
(1) Remove ignition cables and measure the resis-
tance of the cables. Resistance must be within the
range shown in the Cable Resistance Chart in Spec-
ifications. Replace any cable not within tolerance.
(2) Disconnect the electrical connector from the
coil pack.
(3) Measure the primary resistance of each coil. At
the coil, connect an ohmmeter between the B+ pin
and the pin corresponding to the cylinders in ques-
tion (Fig. 17). Resistance on the primary side of each
coil should be 0.45 - 0.65 ohm at (70É to 80É F).
Replace the coil if resistance is not within tolerance.
(4) Remove ignition cables from the secondary tow-
ers of the coil. Measure the secondary resistance of
the coil between the towers of each individual coil
(Fig. 18). Secondary resistance should be 7,000 to
15,800 ohms. Replace the coil if resistance is not
within tolerance.
CHECK COIL TESTÐ3.3/3.8L
Coil 1 fires cylinders 1 and 4, coil 2 fires cyl-
inders 2 and 5, and coil 3 fires cylinders 3 and
6. Each coil tower is labeled with the number of
the corresponding cylinder.
(1) Disconnect the electrical connector from the
coil pack (Fig. 19).
(2) Measure the primary resistance of each coil. At
the coil, connect an ohmmeter between the B+ pinand the pin corresponding to the cylinders in ques-
tion (Fig. 20). Resistance on the primary side of each
coil should be 0.45 - 0.65 ohm at 21É to 27ÉC (70É to
80ÉF). A coil that has not been allowed to cool off,
would result in inaccurate measurement results.
Replace the coil if resistance is not within tolerance.
Fig. 17 Terminal Identification
Fig. 18 Checking Ignition Coil Secondary
Resistance
Fig. 19 Ignition Coil Electrical Connector
Fig. 20 Ignition Coil Terminal Identification
NSIGNITION SYSTEM 8D - 9
DIAGNOSIS AND TESTING (Continued)
(3) Remove ignition cables from the secondary tow-
ers of the coil. Measure the secondary resistance of
the coil between the towers of each individual coil
(Fig. 21). Secondary resistance should be 7,000 to
15,800 ohms. Replace the coil if resistance is not
within tolerance.
FAILURE TO START TEST
This no-start test checks the camshaft position sen-
sor and crankshaft position sensor.
The Powertrain Control Module (PCM) supplies 8
volts to the camshaft position sensor and crankshaft
position sensor through one circuit. If the 8 volt sup-
ply circuit shorts to ground, neither sensor will pro-
duce a signal (output voltage to the PCM).
When the ignition key is turned and left in the On
position, the PCM automatically energizes the Auto
Shutdown (ASD) relay. However, the controller de-en-
ergizes the relay within one second because it has
not received a camshaft position sensor signal indi-
cating engine rotation.
During cranking, the ASD relay will not energize
until the PCM receives a camshaft position sensor
signal. Secondly, the ASD relay remains energized
only if the controller senses a crankshaft position
sensor signal immediately after detecting the cam-
shaft position sensor signal.
(1) Check battery voltage. Voltage should be
approximately 12.66 volts or higher to perform fail-
ure to start test.
(2) Disconnect the harness connector from the coil
pack.
(3) Connect a test light to the B+ (battery voltage)
terminal of the coil electrical connector and ground
as shown in (Fig. 22). The B+ wire for the DIS coil is
dark green with an orange tracer.Do not spread
the terminal with the test light probe.(4) Turn the ignition key to theON position.The
test light should flash On and then Off.Do not turn
the Key to off position, leave it in the On posi-
tion.
(a) If the test light flashes momentarily, the
PCM grounded the Auto Shutdown (ASD) relay.
Proceed to step 5.
(b) If the test light did not flash, the ASD relay
did not energize. The cause is either the relay or
one of the relay circuits. Use the DRB scan tool to
test the ASD relay and circuits. Refer to the appro-
priate Powertrain Diagnostics Procedure Manual.
Refer to the wiring diagrams section for circuit
information.
(5) Crank the engine. (If the key was placed in the
off position after step 4, place the key in the On posi-
tion before cranking. Wait for the test light to flash
once, then crank the engine.)
(6) If the test light momentarily flashes during
cranking, the PCM is not receiving a crankshaft posi-
tion sensor signal. Use the DRB scan tool to test the
crankshaft position sensor and sensor circuits. Refer
to the appropriate Powertrain Diagnostics Procedure
Manual. Refer to the wiring diagrams section for cir-
cuit information.
(7) If the test light did not flash during cranking,
unplug the crankshaft position sensor connector.
Turn the ignition key to the off position. Turn the
key to the On position, wait for the test light to
momentarily flash once, then crank the engine. If the
test light momentarily flashes, the crankshaft posi-
tion sensor is shorted and must be replaced. If the
light did not flash, the cause of the no-start is in
Fig. 21 Checking Ignition Coil Secondary
ResistanceFig. 22 Ignition Coil Engine Harness Connector
8D - 10 IGNITION SYSTEMNS
DIAGNOSIS AND TESTING (Continued)
DISASSEMBLY AND ASSEMBLY
DISTRIBUTORÐ3.0L
REMOVAL
(1) Disconnect distributor connector from distribu-
tor (Fig. 6).
(2) Loosen distributor cap retaining screws.
(3) Lift cap of off distributor.
(4) Rotate engine crankshaft until the distributor
rotor points to the intake manifold plenum. Scribe a
mark on the plenum in line with the rotor. The scribe
line indicates where to position the rotor when rein-
stalling the distributor.
(5) Remove distributor hold down nut (Fig. 7).
(6) Carefully lift the distributor from the engine.
INSTALLATION
(1) Position distributor in engine. Make certain
that the O-ring is properly seated on distributor. If
O-ring is cracked or nicked replace with new one.
(2) Carefully engage distributor drive with gear on
camshaft. When the distributor is installed properly,
the rotor will be in line with previously scribe line on
air intake plenum.If engine was cranked while
distributor was removed, it will be necessary to
establish proper relationship between the dis-
tributor shaft and Number 1 piston position as
follows:
(a) Rotate the crankshaft until number one pis-
ton is at top of compression stroke.
(b) Rotate rotor to number one rotor terminal
(Fig. 8).
(c) Lower the distributor into the opening,
engaging distributor drive with drive on camshaft.
With distributor fully seated on engine, rotor
should be under the number 1 terminal.
(3) Install the distributor cap. Ensure sure all high
tension wires are firmly in the cap towers.
(4) Install hold-down nut and tighten (Fig. 7).
(5) Connect distributor electrical connector to dis-
tributor (Fig. 6).
CLEANING AND INSPECTION
DISTRIBUTOR CAP
Remove the distributor cap and inspect the inside
for flashover, cracking of carbon button, lack of
spring tension on carbon button, cracking of cap, and
burned, worn terminals (Fig. 9). Also check for bro-
ken distributor cap towers. If any of these conditions
are present the distributor cap and/or cables should
be replaced.
Fig. 6 Distributor Electrical ConnectorÐ3.0L Engine
Fig. 7 Distributor Hold-Down
Fig. 8 Distributor Cap Terminal Routing, View from
TopofCap
8D - 26 IGNITION SYSTEMNS
CONDITION POSSIBLE CAUSES CORRECTION
ERRATIC POINTER
MOVEMENT1. Erratic Message from
another Module.1. (a) Check the BCM using a scan tool If OK, go to
Step (b). If not OK, refer to the BCM section of the
service manual to repair the BCM.
(b) Check the PCM using a scan tool. If OK, go to Step
(c). If not OK, refer to the PCM section of the service
manual to repair the PCM.
(c) Check the speed signal input into the PCM. The
speed signal originates from one of the following
sources:
²A distance sensor for vehicles with 3 speed automatic
transmission. Check continuity from distance sensor to
PCM. If OK, replace distance sensor. If not OK, repair
wiring.
²The Electronic Transmission Control Module (TCM)
vehicles with the 4 speed electronic transmissions.
Check continuity from TCM to engine controller. If OK,
use a scan tool to check TCM. Refer to the electronic
section of the service manual to repair the TCM. If not
OK, repair wiring.
2. Internal Cluster Failure. 2. (a) Perform cluster self diagnostic test and check for
fault codes.
²If the pointer moves during test but still appears
erratic and fault codes 110 or 111 don't appear in the
odometer display, then go to Step (b).
²If fault code 110 is displayed in the odometer, go to
Step (e).
²If fault code 111 appears in the odometer display go
to Step (d).
²If fault codes 905, 920, or 940 are displayed in the
odometer display refer to the fault code chart to identify
which module is causing the fault and repair module.
(b) Replace cluster subdial assembly. To Step (c).
(c) Connect cluster into instrument panel wiring
harness. Place it back into the proper position in the
instrument panel. Put in the top two mounting screws to
hold the cluster in place. DO NOT COMPLETELY
INSTALL CLUSTER TO INSTRUMENT PANEL UNTIL
UNIT IS CALIBRATED AND TESTED. Go to Step (d).
(d) Use a scan tool to calibrate cluster and perform Self
Diagnostic Test. If OK, continue installation. If not OK,
go to Step (e).
Replace main cluster pc board and use a scan tool to
calibrate cluster. If not OK, look at another possible
cause for the speedometer failure.
NSINSTRUMENT PANEL AND SYSTEMS 8E - 5
DIAGNOSIS AND TESTING (Continued)
TACHOMETER DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
NO POINTER
MOVEMENT1. Internal Cluster Failure. 1. (a) Perform Cluster Self Diagnostic Test and check
for fault codes.
²If tachometer pointer moves to calibration points
during test and fault codes 110 or 111 don't appear in
the odometer display then failure is not in the cluster.
Look for another possible cause of failure.
²If the pointer doesn't move during test, go to Step
(b).
²If fault code 110 is displayed in the odometer, go to
Step (b).
²If fault code 111 is displayed in the odometer then go
to Step (f).
²If fault codes 920 or 940 are displayed in the
odometer display refer to the fault code chart to identify
which module is causing the fault an repair module.
(b) Replace main cluster pc board. Go to Step (c).
(c) Connect cluster into instrument panel wiring
harness. Place it back into the proper position in the
instrument panel. Put in the top two mounting screws to
hold the cluster in place. DO NOT COMPLETELY
INSTALL CLUSTER TO INSTRUMENT PANEL UNTIL
UNIT IS CALIBRATED AND TESTED. Go to Step (d).
(d) use a scan tool to calibrate cluster and perform Self
Diagnostic Test. If OK, continue installation. If not OK,
go to Step (e).
(e) Replace subdial assembly and use a scan tool to
calibrate cluster. If not OK, look at another possible
cause for the tachometer failure.
(f) Use a scan tool to calibrate tachometer and perform
Self Diagnostic Test. If OK, stop. If not OK, go to Step
(b).
2. No rpm CCD Bus
Message or Zero rpm
CCD Bus Message from
Engine Controller.2. Check the PCM using a scan tool. Refer to the PCM
section of the manual to properly diagnose and repair.
NSINSTRUMENT PANEL AND SYSTEMS 8E - 7
DIAGNOSIS AND TESTING (Continued)