Yes, they're in the workshop manual download of which is in my signature. If you tell me exact model and age I'll see what I can do but I'm telling you now it's often a broken wire in the loom located around the tailgate hinge. Not always mind but do a search and you'll see.
Open the file named HONDAESM.HTML with Internet Explorer. When it opens you first have to 'Allow blocked content', and later, when it asks if you want to close the window, answer 'No'. You should now get a minimized Explorer window which you then resize to your liking. You should then see the options of the manual.
What's actually wrong with the tailgate, mine went wrong recently and it ended up being a simple fix however I ended up buying used closer unit when all I needed to do was unstick the external handle which was preventing the tailgate from closing properly. To check whether there is a broken wire in the loom at the hinge you have to remove part of the roof liner and visually inspect the loom, did you do that?
I have the ptg up on dash and it's not opening by key fob, interior button by dash or manually from the exterior so I can only open it from the inside by climbing through the car. The motor appears to be working so I am trying to trace the wires back but there are so many.