2003 Johnson ST 55 HP WRL 2 Stroke Commercial Service Manual, PN 5005483, Page 71Get this manual
IGNITION COMPONENTS
COMPONENTS
Flywheel
The flywheel contains permanent magnets necessary to energize the sensor and charge coils Once the flywheel exceeds minimum cranking RPM, the flywheel's magnetic lines of force passing through the sensor and charge coil windings produce voltage in those circuits
Sensor Coil (Ignition Plate)
The sensor coil consists of many windings of wire wrapped around metal laminationOnce the flywheel exceeds minimum cranking RPMthe flywheel's magnetic lines of force, cutting through the sensor coil windings, produce approximately 3VThis voltage is supplied to the power pack to control small electronic switches (SCRs) which, in turn, direct power pack output to the correct ignition coil primary
Power Pack
The power pack has several basic functionsIt stores and distributes the voltage received from the charge coilThe power pack uses electronic switches (SCRs), activated by sensor coil output, to select the correct ignition coil primary winding for firing31276