Express 1500 RWD V8-5.3L VIN T (2004)
Remote Control: Description and Operation
ONSTAR(R) STEERING WHEEL CONTROLS
Some vehicles equipped with the OnStar(R) system have the capability of accessing voice mailboxes and other automated phone systems by means of the
steering wheel controls, while the OnStar(R) personal calling (OPC) feature is in use. If the Talk or Mute button, depending upon the vehicle, on the
steering wheel controls are depressed during an OPC call, the vehicle communication module (VCIM) receives the message on the class 2 serial data bus
from either the radio, the driver information module, or the body control module (BCM). This message is interpreted as a request to turn any spoken
numbers into dual tone multi-frequency (DTMF) tones to be delivered over the airwaves to the phone system the user is communicating with. Complete
instructions for operation of these features can be found in the information provided to the customer with the OnStar(R) system.
The steering wheel controls are a resistor network that consist of multiple momentary contact switches and a series of resistors. The switches and resistor
network are arranged so that each switch has a different resistance value. When a switch is pressed, a voltage drop occurs in the resistor network, which
produces a specific voltage value unique to the switch selected, to be interpreted by either the radio, driver information module, or body control module.
