2004 SR Johnson 2-stroke 40, 50HP Service Manual, Page 85Get this manual
ELECTRICAL CHARGING SYSTEM TESTS
Rectifier Resistance Tests
4 AMP MODELS
Disconnect battery cables at the batterySTEP Disconnect all rectifier leads from terminal boardCalibrate 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 Perform the same procedure on the yellow and yellowblue rectifier leadsNote the readings 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
Replace the rectifier if test results vary
DRC4158