1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 345Get this manual
Key Switch Check (With leakage Tester)
I some conditions, the key switch may be shorting (some leakage) to the other terminals in the key switch, but will not show up with test light or an ohmmeterThis condition may be found by using condenser tester (leakage test) where voltage of approximately 500 volts is applied to the key switch terminals1With all leads disconnected and the key switch in the "0 F" position, connect the black lead of the tester to one of the "M" terminals of the key switch 2Attach the red lead and apply leakage test
of the tester to the "8" terminal
3Repeat test by moving the red lead to each of the terminals and applying the leakage testThe meter will indicate if leakage is present4When applying test to other "M" terminal, turn key to the "ON" position