An electronic height control system for a vehicle chassis air suspension
is modified to provide bimodal operation. In the second mode of operation
the chassis air suspension system is maintain a stationary in a stable,
level position to serve as a base for a mobile aerial lift unit installed
on the vehicle. Operation of the suspension system in its stabilization
and leveling mode is triggered by activation of a vehicle power take-off
unit ("PTO") used to position the aerial lift unit.