If you hold to my teaching, you are really my disciples. Then you will know the truth, and the truth will set you free. (TNIV)
Knowing the truth is consequent to holding to his teaching, honouring him with our faith and obeying him as his disciples. Even if the kai in v.32 is simply translated as 'and' and not 'then', there still seems to be a progression in what he is saying, that knowing follows the doing of faith and obedience.
Of course, we ought to expect just this in the light of the wisdom of the Book of Proverbs, that
The fear of the LORD is the beginning of knowledge (Prov. 1:7a)
A genuine reverence for the LORD which results in changed thoughts and actions is the precondition for knowing - truly knowing.
The implications of this must surely be significant, both pastorally and evangelistically.