There are three wires, BLACK, BLUE, AND PURPLE, which is which?

 

On my '010 FB, the BLACK wire is the ground, the VIOLET (purple) is for the turns, and the BLUE is for the running lights.
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Okay, now Im installing the HD mirrors with the built in turn signals, I know the directions say that these are to not replace the stock turn signals, but I called my local HD and the service guy said its no big deal. The new mirrors have two wires, gray and black, going to assume the black is ground and gray is power, so just wire the violet and blue to the gray and black to black?

 

OP: "...so just wire the violet and blue to the gray and black to black? "

I'm no electrical wiz, but I don't think your plan will work. Connecting the 'violet' to the 'gray' and the 'black' to ground should allow you to have turn sigs, but if you splice the 'blue' onto your new sigs, your sigs will receive constant volts and will always be on, resulting in no flashing when you hit the turn sig switch. Maybe someone here can offer you a work-around.
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the easiest way to do this is to use the y-connectors that are supplied with the mirrors and instead of reconnecting the stock blinkers just put them on the shelf instead!

the LEDs on the mirrors aren't very visible in daylight tho, just so's you know!