1987 Johnson/Evinrude CU Outboards 35A thru 55 Service Manual, Page 162Get this manual
Temperature Switch Test Purpose heat sensitive switch is installed in the cylinder head to monitor engine temperatureThis switch is connected in series with the warning hornIf the switch senses temperature in excess of predetermined limit, contacts close and cause the warning horn to sound continuous tone when the key switch is in the ON position
INote the ensure that temperature s.ensing To operator dUring an overheatmg condition,
Testing
.ca.n alert It IS very important that the warning horn be tested on regular basisSee Warning Horn Test, Section 1
1Inject small amount of isopropyl alcohol into the rubber insulating sleeve and slide it back to expose the knife connectors 2Disconnect the knife connectors Remove the cylinder head water coverRemove the switch from the cylinder head4Using continuity light or ohmmeter, make positive connections to the switchone lead to the switch lead and one lead to the metal portion of the switch