Alternator wiring issues

Hi Fabo I am not sure my alternator is wired correctly. Could be or could just be a bad alternator. I have a purple wire coming from the harness but goes to nothing. Sold the car in 2011 I believe and I purchased it back in 2017. Came wired like this.

Does anyone know where the purple wire goes too and if my alternator should be grounded like it is? I figured touching the motor is the same ground lol.

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