IGNITION SYSTEM
TABLE OF CONTENTS
page page
DESCRIPTION AND OPERATION
IGNITION SYSTEM ........................1
SPARK PLUGS-PLATINUM..................1
COIL ON PLUG...........................1
CRANKSHAFT POSITION SENSOR............2
CAMSHAFT POSITION SENSOR..............3
KNOCK SENSOR..........................5
LOCK KEY CYLINDER......................5
IGNITION INTERLOCK .....................5
REMOVAL AND INSTALLATION
SPARK PLUG ............................5
IGNITION COIL ...........................6
AUTOMATIC SHUTDOWN RELAY.............6
CAMSHAFT POSITION SENSOR—2.7L ........6
CAMSHAFT POSITION SENSOR—3.2/3.5L .....6
CRANKSHAFT POSITION SENSOR............7
KNOCK SENSOR..........................7
COIL CAPACITOR .........................8
IGNITION SWITCH ........................8
LOCK KEY CYLINDER......................9
SPECIFICATIONS
TORQUE ...............................11
SPARK PLUGS ..........................11
DESCRIPTION AND OPERATION
IGNITION SYSTEM
DESCRIPTION
NOTE: All engines use a fixed ignition timing sys-
tem. Basic ignition timing is not adjustable. All
spark advance is determined by the Powertrain
Control Module (PCM).
The distributorless ignition system used on these
engines is referred to as the Direct Ignition System
(DIS). The system’s three main components are the
coils, crankshaft position sensor, and camshaft posi-
tion sensor. The coil on plug ignition system utilizes
an ignition coil for every cylinder, it is mounted
directly over the each spark plug.
OPERATION
The crankshaft position sensor and camshaft posi-
tion sensor are hall effect devices. The camshaft posi-
tion sensor and crankshaft position sensor generate
pulses that are inputs to the PCM. The PCM deter-
mines crankshaft position from these sensors. The
PCM calculates injector sequence and ignition timing
from crankshaft position. For a description of both
sensors, refer to Camshaft Position Sensor and
Crankshaft Position Sensor in this section.
SPARK PLUGS-PLATINUM
DESCRIPTION
The 2.7, 3.2, and 3.5L engines use platinum resis-
tor spark plugs. They have resistance values of 6,000
to 20,000 ohms when checked with at least a 1000
volt tester. For spark plug identification and specifi-
cations, Refer to the Specifications section.
Do not use an ohm meter to check the resis-
tance of the spark plugs. This will give an inac-
curate reading.
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 severe driving conditions.
A thin platinum pad is welded to both or center
electrode end(s) as show in (Fig. 1). Extreme care
must be used to prevent spark plug cross threading,
mis-gaping and ceramic insulator damage during
plug removal and installation.
CAUTION: Cleaning of the platinum plug may dam-
age the platinum tip.
COIL ON PLUG
DESCRIPTION
The engines are equipped with a coil on plug igni-
tion system. Each cylinder has a dedicated coil that
sits atop each plug. No secondary wires are required
and connection from the coil to plug is made with a
boot that is attached to the coil. The combination of
LH IGNITION SYSTEM 8D - 1
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