Steering Wheel Controls

CIRCUIT OPERATION
The Steering Wheel Controls consist of several components. They include the following:

^ Steering Wheel Radio And HVAC (Climate Control) Switches
^ Supplemental Inflatable Restraint (SIR) Coil Assembly
^ Radio
^ HVAC Control

Steering Wheel Radio And HVAC Switches
The Steering Wheel Control Switches control Radio power, volume, station frequency blower speed, and set temperature. 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 Radio for each switch pressed.

The Steering Wheel Control (SWC) Switches use incandescent backlighting. The illumination signal CKT 8 is a Pulse Width Modulated (PWM) signal from the Headlight Switch. The bulbs are serviceable.

SIR Coil Assembly
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 while the Steering Wheel is being turned.

Entertainment And Comfort (E&C) Data Line
The Radio receives the different voltages from the Steering Wheel Switches and transforms these voltages into messages to be used by the audio system for communication of Radio commands and information such as, clock, station frequency tuning and display. The (Regular Production Option (RPO) C68) HVAC system uses the E&C Data Line (CKT 835) to transmit and receive climate control display and command information.