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)
either the crankshaft position sensor/camshaft posi-
tion sensor 8 volt supply circuit, or the camshaft
position sensor output or ground circuits. Use the
DRB scan tool to test the camshaft position sensor
and the sensor circuits. Refer to the appropriate Pow-
ertrain Diagnostics Procedure Manual. Refer to the
wiring diagrams section for circuit information.
IGNITION TIMING PROCEDURE
The engines for this vehicle, use a fixed ignition
system. The PCM regulates ignition timing. Basic
ignition timing is not adjustable.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
TEST
Refer to Group 14, Fuel System for Diagnosis and
Testing.
CAMSHAFT POSITION SENSOR AND CRANKSHAFT
POSITION SENSOR
The output voltage of a properly operating cam-
shaft position sensor or crankshaft position sensor
switches from high (5.0 volts) to low (0.3 volts). By
connecting an Moper Diagonostic System (MDS) and
engine analyzer to the vehicle, technicians can view
the square wave pattern.
ENGINE COOLANT TEMPERATURE SENSOR
Refer to Group 14, Fuel System for Diagnosis and
Testing.
INTAKE AIR TEMPERATURE SENSOR
Refer to Group 14, Fuel System, for Diagnosis and
Testing.
SPARK PLUG CONDITION
NORMAL OPERATING CONDITIONS
The few deposits present will be probably light tan
or slightly gray in color with most grades of commer-
cial gasoline (Fig. 23). There will not be evidence of
electrode burning. Gap growth will not average more
than approximately 0.025 mm (.001 in) per 1600 km
(1000 miles) of operation for non platinum spark
plugs. Non-platnium spark plugs that have normal
wear can usually be cleaned, have the electrodes filed
and regapped, and then reinstalled.
CAUTION: Never attempt to file the electrodes or
use a wire brush for cleaning platinum spark plugs.
This would damage the platinum pads which would
shorten spark plug life.
Some fuel refiners in several areas of the United
States have introduced a manganese additive (MMT)
for unleaded fuel. During combustion, fuel with MMT
may coat the entire tip of the spark plug with a rustcolored deposit. The rust color deposits can be misdi-
agnosed as being caused by coolant in the combustion
chamber. Spark plug performance is not affected by
MMT deposits.
COLD FOULING (CARBON FOULING)
Cold fouling is sometimes referred to as carbon
fouling because the deposits that cause cold fouling
are basically carbon (Fig. 23). A dry, black deposit on
one or two plugs in a set may be caused by sticking
valves or misfire conditions. Cold (carbon) fouling of
the entire set may be caused by a clogged air cleaner.
Cold fouling is normal after short operating peri-
ods. The spark plugs do not reach a high enough
operating temperature during short operating peri-
ods.Replace carbon fouled plugs with new
spark plugs.
FUEL FOULING
A spark plug that is coated with excessive wet fuel
is called fuel fouled. This condition is normally
observed during hard start periods.Clean fuel
fouled spark plugs with compressed air and
reinstall them in the engine.
OIL FOULING
A spark plug that is coated with excessive wet oil
is oil fouled. In older engines, wet fouling can be
caused by worn rings or excessive cylinder wear.
Break-in fouling of new engines may occur before
normal oil control is achieved.Replace oil fouled
spark plugs with new ones.
OIL OR ASH ENCRUSTED
If one or more plugs are oil or ash encrusted, eval-
uate the engine for the cause of oil entering the com-
bustion chambers (Fig. 24). Sometimes fuel additives
can cause ash encrustation on an entire set of spark
Fig. 23 Normal Operation and Cold (Carbon) Fouling
NSIGNITION SYSTEM 8D - 11
DIAGNOSIS AND TESTING (Continued)
plugs.Ash encrusted spark plugs can be cleaned
and reused.
HIGH SPEED MISS
When replacing spark plugs because of a high
speed miss condition;wide open throttle opera-
tion should be avoided for approximately 80 km
(50 miles) after installation of new plugs.This
will allow deposit shifting in the combustion chamber
to take place gradually and avoid plug destroying
splash fouling shortly after the plug change.
ELECTRODE GAP BRIDGING
Loose deposits in the combustion chamber can
cause electrode gap bridging. The deposits accumu-
late on the spark plugs during continuous stop-
and-go driving. When the engine is suddenly
subjected to a high torque load, the deposits partially
liquefy and bridge the gap between the electrodes
(Fig. 25). This short circuits the electrodes.Spark
plugs with electrode gap bridging can be
cleaned and reused.
SCAVENGER DEPOSITS
Fuel scavenger deposits may be either white or yel-
low (Fig. 26). They may appear to be harmful, but
are a normal condition caused by chemical additives
in certain fuels. These additives are designed to
change the chemical nature of deposits and decrease
spark plug misfire tendencies. Notice that accumula-
tion on the ground electrode and shell area may be
heavy but the deposits are easily removed.Spark
plugs with scavenger deposits can be consid-
ered normal in condition, cleaned and reused.
CHIPPED ELECTRODE INSULATOR
A chipped electrode insulator usually results from
bending the center electrode while adjusting the
spark plug electrode gap. Under certain conditions,
severe detonation also can separate the insulator
from the center electrode (Fig. 27).Spark plugs
with chipped electrode insulators must be
replaced.
PREIGNITION DAMAGE
Excessive combustion chamber temperature can
cause preignition damage. First, the center electrode
dissolves and the ground electrode dissolves some-
what later (Fig. 28). Insulators appear relatively
deposit free. Determine if the spark plugs are the
correct type, as specified on the VECI label, or if
other operating conditions are causing engine over-
heating.
SPARK PLUG OVERHEATING
Overheating is indicated by a white or gray center
electrode insulator that also appears blistered (Fig.
Fig. 24 Oil or Ash Encrusted
Fig. 25 Electrode Gap Bridging
Fig. 26 Scavenger Deposits
8D - 12 IGNITION SYSTEMNS
DIAGNOSIS AND TESTING (Continued)
IGNITION TIMING PROCEDURE
The 2.4, 3.0, and 3.3/3.8L engines use a fixed igni-
tion system. Basic ignition timing is not adjustable.The Powertrain Control Module (PCM) regulates
ignition timing.
Fig. 34 PDC Rear Bracket
Fig. 35 PCM 40-Way Connectors
Fig. 36 PCM Removal/Installation
NSIGNITION SYSTEM 8D - 15
SERVICE PROCEDURES (Continued)
2.4L ENGINE
INDEX
page page
DESCRIPTION AND OPERATION
CAMSHAFT POSITION SENSOR............ 17
CRANKSHAFT POSITION SENSOR.......... 16
FIRING ORDERÐ2.4L.................... 16
INTAKE AIR TEMPERATURE SENSORÐ2.4L . . . 17
REMOVAL AND INSTALLATION
CAMSHAFT POSITION SENSOR............ 19
CRANKSHAFT POSITION SENSOR.......... 19
ENGINE COOLANT TEMPERATURE SENSORÐ
2.4L................................. 20
IGNITION COILÐ2.4L..................... 18
INTAKE AIR TEMPERATURE SENSORÐ2.4L . . . 21KNOCK SENSORÐ2.4L................... 21
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSORÐ2.4/3.3/3.8L.................. 20
SPARK PLUG CABLE SERVICEÐ2.4L........ 18
SPARK PLUG SERVICE................... 18
THROTTLE POSITION SENSOR............ 20
SPECIFICATIONS
IGNITION COIL......................... 22
SPARK PLUG CABLE RESISTANCEÐ2.4L..... 22
SPARK PLUG........................... 22
TORQUE.............................. 22
DESCRIPTION AND OPERATION
FIRING ORDERÐ2.4L
CRANKSHAFT POSITION SENSOR
The PCM determines what cylinder to fire from the
crankshaft position sensor input and the camshaft
position sensor input. The second crankshaft counter-
weight has machined into it two sets of four timing
reference notches and a 60 degree signature notch
(Fig. 1). From the crankshaft position sensor input
the PCM determines engine speed and crankshaft
angle (position).The notches generate pulses from high to low in
the crankshaft position sensor output voltage. When
a metal portion of the counterweight aligns with the
crankshaft position sensor, the sensor output voltage
goes low (less than 0.3 volts). When a notch aligns
with the sensor, voltage switches high (5.0 volts). As
a group of notches pass under the sensor, the output
voltage switches from low (metal) to high (notch)
then back to low.
If available, an oscilloscope can display the square
wave patterns of each voltage pulse. From the width
of the output voltage pulses, the PCM calculates
engine speed. The width of the pulses represent the
amount of time the output voltage stays high before
switching back to low. The period of time the sensor
output voltage stays high before switching back to
low is referred to as pulse width. The faster the
FIRING ORDERÐ2.4L
Fig. 1 Timing Reference Notches
8D - 16 IGNITION SYSTEMNS
engine is operating, the smaller the pulse width on
the oscilloscope.
By counting the pulses and referencing the pulse
from the 60 degree signature notch, the PCM calcu-
lates crankshaft angle (position). In each group of
timing reference notches, the first notch represents
69 degrees before top dead center (BTDC). The sec-
ond notch represents 49 degrees BTDC. The third
notch represents 29 degrees. The last notch in each
set represents 9 degrees before top dead center
(TDC).
The timing reference notches are machined to a
uniform width representing 13.6 degrees of crank-
shaft rotation. From the voltage pulse width the
PCM tells the difference between the timing refer-
ence notches and the 60 degree signature notch. The
60 degree signature notch produces a longer pulse
width than the smaller timing reference notches. If
the camshaft position sensor input switches from
high to low when the 60 degree signature notch
passes under the crankshaft position sensor, the
PCM knows cylinder number one is the next cylinder
at TDC.
The crankshaft position sensor mounts to the
engine block behind the generator, near the oil filter
(Fig. 8).
CAMSHAFT POSITION SENSOR
The PCM determines fuel injection synchronization
and cylinder identification from inputs provided by
the camshaft position sensor and crankshaft position
sensor. From the two inputs, the PCM determines
crankshaft position.The camshaft position sensor attaches to the rear
of the cylinder head (Fig. 2). A target magnet
attaches to the rear of the camshaft and indexes to
the correct position (Fig. 3). The target magnet has
four different poles arranged in an asymmetrical pat-
tern. As the target magnet rotates, the camshaft
position sensor senses the change in polarity (Fig. 4).
The sensor output switch switches from high (5.0
volts) to low (0.30 volts) as the target magnet rotates.
When the north pole of the target magnet passes
under the sensor, the output switches high. The sen-
sor output switches low when the south pole of the
target magnet passes underneath.
INTAKE AIR TEMPERATURE SENSORÐ2.4L
The intake air temperature sensor measures the
temperature of the air as it enters the engine. The
sensor supplies one of the inputs the PCM uses to
determine injector pulse width and spark advance.
The intake air temperature sensor threads into the
intake manifold (Fig. 5).
Fig. 2 Crankshaft Position Sensor
Fig. 3 Target Magnet
Fig. 4 Target Magnet Polarity
NSIGNITION SYSTEM 8D - 17
DESCRIPTION AND OPERATION (Continued)
REMOVAL AND INSTALLATION
SPARK PLUG CABLE SERVICEÐ2.4L
The cables insulate the spark plugs and covers the
top of the spark plug tube (Fig. 6). To remove the
cables, lightly grasp the top of the cable. Rotate the
insulator 90É and pull straight up. To replace the
cables, disconnect the cable from the ignition coil.
Ensure the #1 and #4 cables run under the #2
and #3 ignition coil towers. Keep #4 cable away
from the oil fill cap.
SPARK PLUG SERVICE
When replacing the spark plugs and spark plug
cables, route the cables correctly and secure them inthe appropriate retainers. Failure to route the cables
properly can cause the radio to reproduce ignition
noise, cross ignition of the spark plugs orshort cir-
cuit the cables to ground.
Never Wire Brush Spark Plugs.The spark plug
insulator tip is harder than the bristles of wire
brushes. Bristles of wire brushes can leave a conduc-
tive, metallic film on the insulator which could lead
to conductive deposits. Conductive deposits can cause
spark plug failure and engine misfire. Use a jewelers
file to remove deposits from the electrode gap or use
a spark plug cleaning machine to clean spark plugs.
REMOVAL
Always remove cables by grasping at the boot,
rotating the boot 1/2 turn, and pulling straight back
in a steady motion.
(1) Prior to removing the spark plug, spray com-
pressed air around the spark plug hole and the area
around the spark plug.
(2) Remove the spark plug using a quality socket
with a foam insert.
(3) Inspect the spark plug condition. Refer to
Spark Plug Condition in this section.
INSTALLATION
(1) To avoid cross threading, start the spark plug
into the cylinder head by hand.
(2) Tighten spark plugs to 28 N´m (20 ft. lbs.)
torque.
(3) Install spark plug cables over spark plugs. A
click will be heard and felt when the cable properly
attaches to the spark plug.
IGNITION COILÐ2.4L
REMOVAL
REMOVAL
(1) Remove spark plug cables from coil (Fig. 7).
Always twist the coil boots to break the seal with the
coil and pull straight back on the boot.
(2) Remove ignition coil electrical connector.
(3) Remove ignition coil mounting bolts, throttle
cable bracket or clip.
(4) Remove ignition coil.
INSTALLATION
(1) Reverse the above procedure for installation.
Tighten mounting screws to 12 N´m (105 in. lbs.)
torque.
(2) Transfer ignition cables to new coil pack. The
coil pack towers and cables are numbered with cylin-
der identification.
Fig. 5 Intake Air Temperature Sensor
Fig. 6 Spark Plug Cables
8D - 18 IGNITION SYSTEMNS
DESCRIPTION AND OPERATION (Continued)