1995 Johnson/Evinrude Outboards 9.9, 15 four-stroke Service Manual, Page 200Get this manual
1 Rectifier Ohmmeter Tests
INote Disconnect battery cables before proceeding with this check
OJ 1Disconnect all rectifier leads from engine wiring harnessOJ 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 indicate the diode is damaged
3Repeat Step using the rectifier yellow lead Results should be similar4Repeat Step using the rectifier gray lead Results should be similar5Move ohmmeter lead