Here is a post I wrote for someone asking questions about installing grips on their 2015 Road Glide.
I have a 15 Ultra Limited and had the dealer put on Slipstream heated grips, love them! First off, as previously mentioned, get the HD service manuals! Secondly, you are going to need to purchase the electrical connection kit P/N 69200722 if you are buying the heated grips. Lastly, the left grip is glue less, regardless of heated or non heated, the end of the grip closest to the switch is shaped to fit inside the switch housing so when everything is tightened (switch housing, clutch lever) the grip is snug and won't move, now to the problem. When tightening the the switch housings to torque specs you may end up with a gap where the front housing meets the rear housing, if you tighten more to try to eliminate that gap, you will find that your horn button becomes jammed and you may damage the internal wiring of the switch assembly. Yesterday I had to take my bike in and have the switch assembly replaced, warranty item, because the trigger switch witch is on top of the left left switch housing, stopped working, I was told that it probably wasn't due to over tightening of the switch housing but probably a defect, I think it was from over tightening. What the dealer had to do to get the switch housings to fit properly was trim down the inside of the left grip where it fits in the groove of the switch housing so the two pieces fit together with no gaps, do not trim off too much, you don't want that grip moving. I would remove the housings from the handle bar and put them together on the grip to see if there is an issue before installing the grip. Get the service manual, it was $48 from Kutter Harley Online. If you have any questions, ask! Good Luck!