1992 Johnson Evinrude "EN" 60 thru 70 Service Manual, P/N 508144, Page 116Get this manual
Blocking DiodeElectric Models
If the S.L.OWwarning system is activated when warning horn receives no oil, low oil, or fuel vacuum signal, test engine harness blocking diode1Disconnect engine harness red connector2Disconnect temperature switch tan leadf31 3Calibrate ohmmeter on appropriate scaleConnect between tan lead and engine harness tan pin Note reading4Reverse meter connections or press "polarity" button Note reading high reading in one direction and low reading in the other direction indicates the diode is good5Replace engine harness blocking diode if your test results vary6Complete all circuits disconnected during this testDR2344