1971 Johnson 60HP outboards Service Manual, Page 77Get this manual
A test light may be used in place of meterUnder no circumstances use any test meter or instrument with more than 12-volt source1Disconnect rectifier connectorConnect one ohmmeter (HI ohms scale) lead to either yellow rectifier lead, and other meter lead to groundNote meter reading
2Reverse test leads and again note meter readingAn infinite (very high) reading in both checks indicates the diode is openA zero reading in both checks indicates the diode is shortedA normal diode will show reading in one direction and no reading in the other direction3Repeat this procedure with other rectifier yellow lead4Repeat test, connecting meter between each rectifier yellow lead and the rectifier red leadTo check stator windings, disconneCt the yellow leads at the power headConnect the red meter lead to either yellow lead and black lead to ground to check for shortsAn infinite reading on HI ohms scale indicates the windings are goodConnect the ohmmeter (LO ohms scale) between the two yellow leadsA reading of .75 ohms .2 indicates the windings are good, and an infinite reading indicates the windings are openSee Figure 7-15REPLACEMENT OF ALTERNATOR