A method and system are set forth for leveling a vehicle chassis supported on air springs. The system and method include a position switch at each air spring which is adapted to generate a signal when the spring is compressed to or beyond a desired length representing the desired level for the vehicle chassis. Based upon the duration of the signal over a time interval a duty cycle for the spring is established. If the duty cycle is below a desired valve or range of valves this indicates the chassis is too high and the system incrementally deflates the spring. If the duty cycle is above the desired valve or range of valves this indicates the chassis is too low and the spring is incremetally deflated. Accordingly, leveling can take place when the vehicle is in motion.