1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 59Get this manual
Warning Horn Test (At Control) A check of the warning horn can be made by turning the key switch to the "On" position and inserting another key or thin piece of metal into the slot in the controlThe horn should soundIf the horn does not sound check the horn and complete systemWarning Horn Test (At Motor) order to benefit from the warning horn, it must be in operating conditionIt is advisable to check the horn at the start of each boating season and periodically during the season
Test Procedure
1Slide the insulating sleeve to one side of wire and expose the quick disconnect between the temperature switch and the horn lead2Touch terminals to unpainted surface of the powerhead to ground3With the ignition switch in the liOn" position the horn should soundIf the horn does not sound but other electrical components function correctly, the horn or wiring may be damagedRepair or replace as requiredRefer to Section 4, Powerhead to test temperature switch
Submerged Motor