1998 Johnson Evinrude EC 5 thru 15 HP Four Stroke Service Manual, Page 320Get this manual
Rectifier Ohmmeter Tests9.915 (305cc)
INote Disconnect battery cables before proceeding with this check
rn 1Disconnect all rectifier leads from engine wiring harnessrnother lead ohmmeter on appropriate scaleNote the readingReverse cleanohmmeter connections or 2Calibrate Connect one lead to engine groundConnect the to the rectifier yellowgray leadthe
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
rn 3Repeat Step using the rectifier yellow lead Results should be similar