If a person tapers off vicodine, from 4.0,2.0, 05 then 0 for 1.5 days do you think it will be such a low amount that it will not show up in a urine test?

As long as one is taking vicodin it will show up.

Depends on the test. Some tests don't show positive if the Vicodin is only being taken at or below the terapeutic level.