2003 Johnson ST 6/8 HP 4 Stroke Outboards Service Manual, PN 5005471, Page 78Get this manual
IGNITION SYSTEM TESTS Ohmmeter Ground Test To test for grounded condition, connect ohmmeter, alternately, between each connector and clean engine ground Any needle movement indicates sensor coil or leads are grounded Locate and repair groundor replace sensor coilComplete all circuits disconnected during this test
STEP Connect ohmmeter red lead to one of the coil's spark plug terminalsLeave meter black lead connected to ground tab Meter must show high reading On two-cylinder models, move meter red lead to remaining coil spark plug terminal Meter must show high reading
Ignition Coil Tests
Resistance Tests
STEP Resistance tests may be performed while the ignition coil is still mounted on the powerheadTwist and remove the spark plug leads and primary coil lead from the ignition coilConnect ohmmeter black lead to clean engine groundIf the coil is not mounted on the engine, connect meter black lead to ground tab on the coilConnect meter red lead to coil primary terminalMeter must show: 0.1 0.05 ohms for HP models 0.28 0.05 ohms for HP models