[FirstYorkie]

This will sound gross but try taking some of his poop outside and leave it there. Direct him to it when you take him outside. Dogs often stimulate themselves to defecate by smelling their own (old) poop.

Be sure that you praise and reward heavily when he does go outside!

Personally, I don't think using the crate is necessary (but many swear by it). I would just watch him like a hawk and swoop down and take him outside when he gets ready to go inside. If he finishes outside, have a party!