1997 Johnson Evinrude "EU" 40 thru 55 2-Cylinder Service Manual, P/N 507265, Page 285Get this manual
Rectifier Ohmmeter Tests4-Amp Models
INote Disconnect battery cables before proceeding with this check
rn 1Disconnect all rectifier leads from the terminal boardrn clean engine groundConnect the other leadConnect one lead 2Calibrate ohmmeter on appropriate scaleto 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
rn 3Repeat Step using the rectifier yellow lead Results should be similar