1991 Johnson/Evinrude Models "EI" 40 thru 55 Service Manual, Page 279Get this manual
Rectifier Ohmmeter Tests Disconnect battery cables before proceeding with this check1Disconnect all rectifier leads from the terminal board
L!J 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 similar5Move meter lead from engine ground to rectifier red leadf516Repeat Step with meter 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 similar1!18Repeat Step using rectifier red and yellowblue leads Results should be similar