Vehicle steering column control system

A control circuit is provided for transferring power and communication signals through a wireless coupling device in a vehicle steering column. The device can include a rotary transformer having a primary and secondary magnetic structure respectively associated with the wheel side and column side of the steering column. A squib power circuit transforms a high energy power signal suitable for firing an air bag from the column side to the wheel side. A low energy power circuit generates a signal from the column side to the wheel side suitable for operating isolated wheel side electronics, such as cruise control and the like. A tone encoder and decoder circuit communicates low level control signals suitable for signaling wheel side commands from the wheel side to the column side. The low energy power circuit and the tone encoder circuit operate simultaneously and continuously without signal debilitating interaction. An alternative embodiment avoids the low energy power circuit and the encoder and decoder circuit and includes a pulse circuit to impress a test signal on the wheel side to generate a ring signal representative of air bag firing operability and whether a horn switch is depressed.