Stator Winding Test

Turn ignition switch "OFF". Using a voltmeter, check voltage on any of the 3 phases of stator windings, accessible through ventilation holes.
Connect voltmeter negative lead to ground and positive lead to phase winding. See Fig 1. Voltmeter should indicate zero (0) volts.

Fig 1: Checking Voltage Between Stator Windings and Ground
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Insert voltmeter positive probe through ventilation hole .
Connect negative lead to phase winding, and positive lead to alternator's output terminal (B +). See Fig 2. Again, voltmeter should read zero (0) volts.

Fig 2: Checking Voltage Between Stator Windings and Alternator Positive Terminal
Courtesy of NOT AVAILABLE

Insert negative probe through ventilation hole .
Any reading other than zero (0) volts in steps 2) and 3) indicates a defective positive rectifier diode. Replace diode bridge.