Your vehicle may have an air suspension seat. There are two ways you can adjust the seat.

The height adjustment is controlled by the air suspension valve. The lever for the valve is located on the outboard side of the driver's seat.

Pull the lever up to raise the seat. Push the lever down to lower the seat.

The lever is located on the inboard side of the driver's seat.

Move the handle down to lock the seat in place. This is used to reduce backslap experienced while in tractor/trailer operation or while operating a dump truck.