2004 SR Johnson 2-stroke 40, 50HP Service Manual, Page 112Get this manual
IGNITION COMPONENTS
Sensor Coil (Timer Base and Sensor Coil Assembly)
The sensor coil consists of many windings of wire wrapped around metal laminationOnce the flywheel exceeds minimum cranking RPM, the flywheel's magnetic lines of force pass through the sensor coil windings to produce approximately
Power Pack
The power pack has several basic functionsIt stores and distributes the voltage received from the charge coilThe power pack uses electronic switches, activated by sensor coil output, to select the correct ignition coil primary winding for firing