1994 Johnson/Evinrude "ER" 9.9 thru 30 outboards Service Manual, Page 148Get 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 positionTo 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 Horn, Section 1Testing f311Disconnect the bullet connector(s) and remove 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 switchf413Place the switch and an accurate industrial thermometer in warm automotive crankcase oil4Slowly increase the oil temperature using an external heat sourceTo avoid possible fire or explosion: Use suitable container for the oil Use an oil that has flashpoint above 300 (150 C), such as OMC Cobra 4-Cyce Motor Oil Do not use open flame as heat source5The switch must react to the changing temperature as follows: Wire Color Tan TanRed Switch Closed