Shock collars do work. I would set the dog up by dropping him right on top of trash. That way you know he's running trash and you should be close enough to get full contact with the collar.
I would caution you to make sure your dog is well started running and treeing coon so that he knows what he's after. If your sure he's well started take him by himself. If he runs and trees coon great. If he runs trash light him up.