The rear is locked in 4 wheel.
Did you follow this video?
I have seen a lot of posts about Pioneer's making a clanking/banging sound when shifting from 2WD to Turf Mode. I have made a video detailing how to fix this and what causes that. Please like and subscribe and I hope this helps some of you!
hondasxs.com
It can be fussy. You can start with the alignment described in the service manual as a baseline, but mine is pretty far from there to work properly.