Exterior, 1990 Chevrolet School Bus (21 Seats) 1-School Bus Pass by 2-School Bus Pass by 3-Car Trailer Pass by 4-School Bus Approach Slowdown Stop Short Idle Shutoff, Manually Open Door then Close Door, Start Motor Revving Acceleration Away 5-School Bus Approach Slowdown Stop Long Idle Motor Revving Idle and Shutoff 6-School Bus Start Motor Idle with Pistons Clacking Motor Revving Idle and Shutoff