Abstract: A warning sign hinge-mounted on the side of a vehicle, for warning motorists against blocking access, as by parking in close proximity, of a wheelchair to a wheelchair lift aboard the vehicle. The sign includes warning indicia and reflectors, and has a distinctive shape. The sign is manually latched to the vehicle side when not in service, and manually released for deployment. Springs urge the sign into the deployed position perpendicular to the vehicle side when not latched in the stowed position.