I found a ground wire completely disconnected, but I do not know what it should be grounding. I've checked the wiring diagrams - I can't tell if it should ground the transmission and/or engine.   Any help appreciated.

[2015 Z Force 800 53/Trail EPS]

If it's several small wires on one eyelet I would say it's a chassis ground. It has to go to the engine case somewhere along with the main negative cable from the battery. Most often on one of the CVT cover bolts if that cover is aluminum. Otherwise trace the battery ground to the case and put it with it if possible. But if it's one single larger cable and it is not the battery ground, then it's possible its one of the winch motor cables and it has to go to the battery.

It's several small wires. The CVT cover is missing one of the bolts and the wire seems to be the right length for it to connect there, so that's where I put it.  So far, so good. I did have a parasidic power drain that I have yet to diagnose. Will be curious to see if this is the cause.

Thanks

[2015 Z Force 800 53/Trail EPS]

There will always be some parasitic draw because of the clock and other setting memory needs but it should be less then 350 milliamps. CFM machines have the highest of any I heard of and that's why many batteries get pretty low after only a few weeks of sitting. It's also why it's a good idea to keep them on a smarty charger or tender when sitting.