1998 Johnson Evinrude "EC" 25, 35 HP 3-Cylinder Outboards Service Manual, Page 124Get 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 systemIf the switch senses temperature in excess of predetermined limit, contacts close and cause the System Check gauge "WATER TEMP" light to turn on, and the warning horn to sou nd for ten seconds
INote To ensure that the temperature sensing
system can alert the operator during an overheating condition, test the warning system as described in Section 8, System Check Engine Monitor
Testing
1Disconnect the temperature switch connectorRemove the temperature switch from the cylinder head