When in draft mode, there is feedback through the top link or the lower lift arms. When a change in drag force occurs due to a change in soil type, the increased or decreased draft causes the control system raise or lower the ground enagaing implement (plow). I believe the higher the draft lever is the less change it takes to cause the control to be active. I don't any plowing so I might not have this quite right but if it isn't correct someone will challenge it.