An access system for a vehicle includes a gateway module that connects to the vehicle data bus, and an interface system coupled to the gateway module via a gateway bus. The interface system is also coupled to a ramp control subsystem that operates to stow and deploy a ramp for providing wheelchair access to the vehicle. A door control subsystem is coupled to the vehicle data bus and operates in response to data signals sent over the vehicle data bus. The gateway module is configured to relay signals relating to the status of the ramp from the gateway bus to the vehicle data bus to coordinate operation of the door and the ramp.