1996 Johnson/Evinrude Outboards 25, 35 3-Cylinder Service Manual, Page 266Get 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 section 3To test the instrument harness warning circuits, turn the engine key switch to ON position rn 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 sound for 10 seconds6After 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 ontroubleshoot the corresponding circuit for an open in the instrument harnessNO OILTanIYellow Circuit WATER TEMPTan Circuit LOW OILTanBlack Circuit Tachometer Function 1Turn the engine key switch to ON position[] 2Move tester TACH ONOFF switch to ON position3The tachometer should read approximately 3200 RPM If the tachometer does not indicate this reading, check the instrument harness gray, black, and purple circuits for an open If the gray, black, and purple circuits are OK, replace tachometerNO OIL