1997 Johnson/Evinrude EU 25, 35 HP 3-Cylinder outboards Service Manual, Page 258Get this manual
If the gauge lights do not turn on or if the warning horn does not sound for 12 second, test the gauge and wiring as described in Circuit Verification, Instrument Harness, this section3To test the instrument harness warning circuits, turn the engine key switch to ON position TACH
W 4Move tester TACH ONOFF switch to ON position[!]
5Press the tester NO OIL buttonThe gauge NO OIL light should turn on for 30 seconds, and the warning horn should sou nd for 10 seconds
" SYSTEMATCM
6After waiting for NO OIL light to turn off, press the OVERHEAT buttonThe appropriate light should turn on, and you should find the same test results as Step 5Then check the LOW OIL circuit If the gauge lights do not stay on for 30 seconds, troubleshoot the instrument harness gray circuit for an open If one or more gauge lights do not turn on, troubleshoot the corresponding circuit for an open in the instrument harnessNO OILTanlYeliow Circuit WATER TEMPTan Circuit LOW OILTanBlack Circuit