Abstract: One or more support plates are secured to frame portions of a motor vehicle each in proximity to one of the wheel suspension systems of the vehicle. Hingedly mounted on each support plate is a control plate. Each control plate has a free end positioned to coact with a portion of the wheel suspension system (wheel balancer, upper or lower control arm, shock absorbers, springs) and more particularly that portion of the wheel suspension system which will drop or move downwardly when the vehicle is jacked up in preparation to remove a tire. A mounting bracket is adjustably carried by each support plate in proximity to the control plate hingedly carried thereby. An electrical switch is positioned on each mounting bracket with the operating element for its contacts positioned for coaction with its respective control plate to be operated thereby in response to movement of the associated movable portion of the wheel suspension system.