1987 Johnson/Evinrude CU Outboards 35A thru 55 Service Manual, Page 53Get this manual
Warning Horn Test
INote To avoidinpossible powerhead damage, be sure to check the the warning horn is operating conditionIt is advisable
horn at the start of each boating season and periodically during the seasonAt Remote 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 sound If the horn does not sound, check the horn and the complete systemAt the Engine f61 1Inject small amount of isopropyl alcohol into the rubber insulating sleeve and slide it back to expose the knife connectors