Circuit Description

The steering wheel controls consist of two components:
^ Steering wheel Radio/HVAC switches
^ SIR Coil Assembly

The steering wheel switches control various functions of the Radio and HVAC. These switches are actually a ladder network consisting of the switches and a series of resistors. The ladder network is arranged so that each switch has a different resistance. This allows a different voltage output to the HVAC or radio for each switch pressed.

The SIR coil assembly contains four wires used by the steering wheel controls. This allows voltages to be sent from the steering wheel switches to the Radio or HVAC while the steering wheel is being turned.