1992 Johnson Evinrude "EN" 9.9 thru 30 Service Manual, P/N 508142, Page 312Get this manual
Rectifier Ohmmeter Tests
Disconnect battery cables before proceeding with this check1Disconnect all rectifier leads from terminal board
2Calibrate ohmmeter on appropriate scaleConnect one lead to clean engine groundConnect the other lead to the rectifier yellowgray leadNote the readingReverse the ohmmeter connections or press the "reverse polarity" button and note the reading
high reading in one direction and low reading in the other direction indicates the diode is OK Two high readings or two low readings indicates the diode is damaged3Repeat Step using the rectifier yellow lead Results should be similar4Repeat Step using the rectifier yellowblue lead Results should be similarf515Move ohmmeter lead from engine ground to rectifier red f516Repeat Step with ohmmeter leads connected to rectifier red and yellowgray leads high reading in one direction and low reading in the other direction indicates the diode is' OK Two high readings or two low readings indicates the diode is damaged7Repeat Step using rectifier red and yellow leads Results should be similar8Repeat Step using rectifier red and yellowblue leads Results should be similarU