Abstract: A height adjustment system for automatically adjusting the height of the tail of a tilt bed truck in response to changes in the terrain profile. The tail of the bed of the truck is adjustable in height relative to ground level by a lifting mechanism, such as a hydraulic, pneumatic, or electro-mechanical lift. The main components of the height adjustment system include a terrain following member and a support member. The terrain following member follows the terrain profile as the truck traverses the terrain. The support member movably attaches the terrain following member to the bed of the truck proximate the tail. The support member moves relative to the bed of the truck responsive to the terrain profile and is capable of assuming a range of positions, including a first position and a second position. The support member closes a first electrical contact when in the first position and closes a second electrical contact when in the second position.