1995 Johnson/Evinrude Outboards 25, 35 3-Cylinder Service Manual, Page 127Get this manual
Temperature Switch Test Purpose heat sensitive switch is installed in the cylinder head to monitor engine temperatureThe 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 To ensure that the temperature sensing
system can alert the operator during an overheating condition, it is very important that the warning horn be tested on regular basisSee Warning System, Section 1
Testing
1, Disconnect the temperature switch connectorRemove the temperature switch from the cylinder head2Using 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