Engine Ignition (Description and Operation)

Eight separate ignition coils (12029):

• are mounted directly above each spark plug (12405).
• are controlled by the powertrain control module (PCM) for correct firing sequence.

The spark plug:

• changes the high voltage pulse into a spark which ignites the fuel and air mixture.
• originally equipped on the vehicle has a platinum-enhanced active electrode for long life.

Crankshaft position (CKP) sensor (6C315):

NOTE: Initial engine ignition timing is set at 10 degrees +- 2 degrees before top dead center (BTDC) and is not adjustable. For additional information, refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.

• is a variable reluctance sensor triggered by a 36-minus-1 tooth trigger pulse wheel located on the crankshaft (6303) inside the engine front cover (6019).

The sine wave type signal generated from the crankshaft position sensor provides two types of information:

• position of the crankshaft in 10 degree increments
• the crankshaft speed (rpm)

The powertrain control module (PCM) (12A650) uses this information to determine ignition coil turn ON and turn OFF times and misfire detection.

Engine Ignition (DIAGNOSIS AND TESTING)

Refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.