Installation manual

90-898305

6-8

Ignition System - 3 Cylinder 1.5L Models

Theory of Operation

When the ignition key is turned to the RUN position, battery voltage is applied

to the electrical system through the main power relay. If the Propulsion Control

Module (PCM) does not sense engine rotation from the starter motor within a

certain time period, the relay is turned off. Engine rotation will again engage

the relay. When the main power relay is closed, system voltage is supplied

through the dedicated 20 ampere ignition fuse to the positive terminal of all 3

ignition coils. Each coil contains an internal driver circuit. The driver circuit

switches the primary current on for a given time period (dwell), and then

switches it off causing the collapse of the coil’s magnetic field which creates a

spark. The Crank Position Sensor reads the encoder tooth pattern on the

flywheel which allows the PCM to monitor the position of the crankshaft while

the engine is running. At the proper time for ignition spark, the PCM sends a

digital signal to the coil driver commanding the driver to dwell and then provide

spark. When the engine is operating at lower RPM, this process is repeated in

quick succession to provide a multi-strike spark for each combustion event.

The number of strikes per event is varied depending on RPM and load

requirements. The spark plug features an extended protrusion into the

combustion chamber and platinum tips on both the center and ground

electrode.

Note: Ignition load test was not operational until PCM part number 885557

047 for 115 HP, 885557046 for 90HP and 885557001 for 75 HP introduced

late 2004.

Notes

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