If your STS came from the factory with heated grips it was a mistake. What makes you think it did? To add heated grips you need the switch and the grip heaters. That is what you get in the kit in the catalog. Yes the wiring is there, but you need more than that.
710002354 Switch, Heat Grip $42.99 CAD
709400929 Throttle Heating Grip. ST-LTD $314.99 CAD
709400625 Heating Handle Grip. ST-LTD $164.99 CAD
Those are Canadian prices so the US price should be about 20% less.
http://www.spyderlovers.com/forums/a...d=120143&stc=1
That is the US price and it's a whole lot cheaper than buying the parts.