1998 Johnson Evinrude "EC" 25, 35 HP 3-Cylinder Outboards Service Manual, Page 248Get this manual
WATER TEMP Circuit
1Separate the connector between the engine harness and the temperature switch
2Using jumper wire, connect the engine harness tan lead
to clean engine ground3Turn the key switch to ON positionAfter the normal self-test sequence, the gauge WATER TEMP light should stay on If WATER TEMP light is not on, troubleshoot tan circuit for an open in the engine harness or the instrument harness42866
4On engines, test both temperature switch tan circuits
5To test the temperature switch itself, refer to Temperature
Switch, Section 46Turn the key switch OFF and reconnect all circuits disconnected during these testsLOW OIL Circuit