1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 148Get this manual
41 Key Switch Stop Circuit Test 65 and 155 Models
1Separate the four-wire connector between the power pack and ignition coils2Calibrate the ohmmeter to high ohms scaleConnect the meter red lead (+) to the "0" terminal in the ignition coil end of the connector, and the meter black lead (-) to clean engine groundto liOn," and place the cap and 3Turn the key switch lanyard assembly on the emergency ignition cutoff switch 4The meter should indicate an open circuit (00)If there is any needle movement, remove the blackyellow stripe wire from the key switch "M" terminal and the emergency ignition cutoff switch with the ohmmeter still connected5If the meter indicates an open circuit (00) with the wire removed from the key switch, check the key switch, and the emergency ignition cutoff switchIf closed circuit (0) is indicatedrepair or replace the blackyellow stripe lead between the key switch and ignition coil end of the four-wire connector6Turn key switch to "Off" positionMeter should indicate closed circuit7If meter does not indicate closed circuit, check key switch, key switch ground lead, blackyellow stripe lead and emergency ignition cutoff switch for open circuitRepair circuit 8If engine does not stop when key switch is turned to "Off" position, and stop circuit checks out ok, check power pack grounding circuit Refer to Rough Running Engine155 Model, steps 1-4, on page 3-183-17