Additional info read the service manual. There's a procedure in there to check alternator field current draw. For that you need a multimeter with an ammeter scale, and if they have one, usually either 10A or 20A will do
One reason the field current test might be important, is that a field can become partially shorted, drawing too much current, and can burn up the VR. Or the brush holders can have problems and create shorts
IF YOU REPLACE the alternator CHECK THE NEW ONE for shorts problems at the brushes
