2003 Johnson ST 6/8 HP 4 Stroke Outboards Service Manual, PN 5005471, Page 80Get this manual
IGNITION FLYWHEEL
This ignition system incorporates the S.LoW (Speed Limit Overheat Warning) system,which gradually limits engine speed to approximately 2000 RPM when crankcase oil pressure drops to dangerously low levelTo resume normal tion after the S.LoW warning system has activated, the engine must be brought to an idle and oil pressure must be restoredThe S.L.OW warning system depends on input from the oil pressure switch tan lead
S.L.OWarning System Test
FLYWHEEL
The flywheel magnets must be of particular strength to produce the voltage necessary to run an ignition systemWeak flywheel magnets can cause low ignition voltage and affect engine performanceLow ignition output readings on ignition test equipment such as the peak-reading voltmeter can lead to unnecessary replacement of ignition componentsAn accurate alternator output test can help determine the flywheel's conditionRefer to Running Alternator Output Test in ELECTRICAL section