VUE AWD V6-3.5L VIN 4 (2004)
Global Positioning System Module: Description and Operation
VEHICLE COMMUNICATION INTERFACE MODULE (VCIM)
The VCIM is a 3-watt cellular device that allows the user to communicate data and voice signals over the national cellular network. It is powered by a
fused, battery positive voltage circuit, connected through vehicle wiring to the 3-button assembly and the radio, and attached by means of coax cables to
the cellular and navigation antennas. Ground for the module is accomplished by means of dedicated circuits that are routed with body wiring systems to
chassis ground points. The module houses two modems, one to process global positioning system (GPS) data, and the other for cellular information.
Satellites orbiting earth are constantly transmitting signals of their current location, from which the OnStar(R) system is able to pinpoint its own location.
The navigation antenna receives these GPS signals and provides the data to the VCIM to be processed. The VCIM communicates with the rest of the
vehicle over the class 2 serial data bus. Ignition state is determined by the VCIM through class 2 messaging. The module also has the capability of
commanding the horn, door lock/unlock and operating the exterior lamps using the class 2 serial data circuit. When an OnStar(R) keypress is made, a
class 2 message is sent to the audio system to mute all radio functions and transmit OnStar(R) originated audio. After the audio system is muted, the
OnStar(R) signals are transmitted to the audio system on the cellular telephone voice signal circuit, and returned to the module on the cellular telephone
voice low reference circuit. The cellular modem connects the OnStar(R) system to the cellular carrier's communication system by interacting with the
national cellular infrastructure. The module sends and receives all cellular communications over the cellular antenna and cellular antenna coax.
OnStar(R) Button Assembly
The OnStar(R) button assembly may be part of the rearview mirror on some vehicles or a separate unit on others. The button assembly is comprised of
3 buttons and a status LED. The buttons are defined as follows:
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The Answer/End Call button, which is black with a white "dot" allows the user to answer and end calls or initiate the personal calling feature, if
equipped.
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The blue OnStar(R) Call Center button, which displays the OnStar(R) logo, allows the user to connect to the OnStar(R) call center.
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The Emergency button, which will display either a red or white cross, sends a high priority emergency call to the OnStar(R) call center when
pressed.
The OnStar(R) button assembly receives 10 volts on the keypad supply voltage circuit. When pressed, each button completes a circuit across a resister
allowing a specific voltage to be returned to the VCIM on the keypad signal circuit. Depending upon the voltage range returned, the VCIM is able to
identify which button has been pressed.
The OnStar(R) status LED is located to the right of the emergency button on a mirror-mounted assembly and to the left of the answer/end call button
when the assembly is mounted on the dash or overhead console. The LED is green when the system is on and operating normally. When the status
LED is green and flashing, it is an indication that a call is in progress. When the LED is red, this indicates a system malfunction is present. In the event
there is a system malfunction and the OnStar(R) system is still able to make a call, the LED will flash red during the call. The OnStar(R) LED is
controlled by the VCIM over the keypad red LED signal circuit and the keypad green LED signal circuit.
OnStar(R) Microphone
The OnStar(R), or cellular, microphone can be part of the rearview mirror assembly, or on some vehicle lines, can be a separate, stand alone unit. In
either case, the microphone is supplied voltage on the cellular microphone signal circuit, while voice data from the user is sent back to the VCIM by
means of either a cellular microphone low reference circuit or a drain wire.
Onstar(R)
OnStar(R) equipped (RPO UE1) vehicles use the radio amplifier and speaker system for voice communication from the OnStar(R) operator to the
vehicle. Voice communication from the vehicle to the OnStar(R) operator is through the OnStar(R) microphone and module, which is not a part of the
radio system.
When OnStar(R) begins operation, the radio volume is set to a preset level, autotone preset for OnStar(R) becomes active and the fade control is
adjusted to the full front speakers. The radio volume control can then be used to adjust the volume to a desired level.
The radio system and OnStar(R) system are connected through the 12-way connector at the back of the radio. Left and right channel OnStar(R) audio,
mute control of radio functions by OnStar(R), and the audio signal ground are the circuits provided in the 12-way connector.
Disconnecting the 12-way connector from the radio will isolate the radio system from the OnStar(R) system. Voice communication from the vehicle to
the OnStar(R) operator could be possible under this condition. However, the vehicle occupant will not be able to hear the OnStar(R) operator.
For more information regarding radio operation problems, refer to Symptoms - Radio, Stereo and Compact Disc and Diagnostic System Check -
Radio, Stereo and Compact Disc. For further information regarding OnStar(R) operation, refer to the OnStar(R) section of this service data.
