1996 Johnson Evinrude "ED" 9.9 thru 30 2-Cylinder Service Manual, P/N 507122, Page 330Get this manual
If the gauge lights do not turn on or if the warning horn does not sound for 112 second, test the gauge and wiring as described in Circuit Verification, Instrument Harness, this sectionTACH
3To test the instrument harness temperature warning circuit, turn the engine key switch to ON position
4Move tester TACH ONOFF switch to ON position
[] 5Press the tester OVERHEAT buttonThe gauge WATER TEMP light should turn on for 30 seconds, and the warning horn should sound for 10 seconds If the WATER TEMP light does not stay on for 30 seconds, troubleshoot the instrument harness tan circuit for an openTachometer Function