Chevrolet Equinox Service Manual: Radio/Audio System Description and Operation (with Monochrome Display)

The entertainment system on this vehicle may have several different configurationsavailable to it. To determine the specific configuration of the vehicle, please seethe Service Parts ID Label, and refer toRPO Code List.

Each item in the list below represents topics covered in detail below.

Radio Circuit OperationInformation Display and ControlsAntenna SystemRadio ReceptionSpeaker OperationAudio Amplifier (If equipped)Theft DeterrentAuxiliary Audio Input Jack (If equipped)Multimedia Player Interface Module (if equipped)USB Port (If equipped)Active Noise Cancellation (If equipped)OnStar-®Steering Wheel Controls (If equipped)Auto Volume ControlRadio Circuit Operation

Radio Power

The radio does not use a discrete ignition feed circuit for power moding. The powermode master provides the system power mode to the radio via serial data messages.The power mode master determines the system power mode by processing power mode informationfrom ignition switch inputs. Serial data power modes supported by the radio are OFF,ACCESSORY, RUN, and CRANK REQUEST.

Radio Grounds

The vehicle harness provides a ground for the radio circuits. The radio may also becase grounded.

Radio Data Link Communication

The radio communicates with other modules via serial data.

Radio Audio Outputs

Each of the audio output channel circuits (+) and (-), at the radio have a DC biasvoltage that is approximately one half of battery voltage. The audio being playedon the system is produced by a varying AC voltage that is centered around the DC biasvoltage on the same circuit. The AC voltage is what causes the speaker cone to moveand produce sound. The frequency (Hz) of the AC voltage signal is directly relatedto the frequency ofthe input (audio source playing) to the audio system. Both the DC bias voltage andthe AC voltage signals are needed for the audio system to properly produce sound.

Remote Enable Output

The remote enable circuit is a discrete 12-V signal supplied to infotainment systemcomponents when the radio is producing audio, needs the front display on, needs videoentertainment system components on, or needs to produce chimes. This signal is usedto control the power state of the components. There is no output on radio the remoteenable circuit when the vehicle is in the CRANK powermode, this is to minimize currentconsumptionfrom the attached modules and also to avoid audio pops during crank events.

Information Display and ControlsRadio/HVAC Communications

(1)	Radio/HVAC Controls
(2)	Info Display Module
(3)	Radio
(4)	HVAC Control Module
(5)	Data Link Connector
(a)	GMLAN
(b)	Local InterconnectNetwork-HVAC
(c)	CAN Graphical Interface
(d)	Local InterconnectNetwork-Radio

The radio/HVAC control is a separate component from the radio. The radio/HVAC controlscontain the radio control knobs and buttons for all audio functions.

The radio/HVAC controls operate radio functions through serial data messages. Theradio/HVAC controls communicate to the info display module through LIN serial data.The info display module communicates to radio through CGI serial data.

When the operator rotates a radio control knob to change radio stations or increasethe volume a message is sent to the radio over serial data. After receiving the messagethe radio will make the adjustment. Messages communicated between the radio and theradio/HVAC controls and info display include the following:

Button presses/knob rotationsInfo display module dimmingRadio/HVAC controls back-lightingGraphics and text information

HVAC data for controls and status indicators is communicated between the radio/HVACcontrols and the HVAC control module with a separate LIN serial data circuit. HVACstatus screen information from the HVAC control module is transmitted to the radioon the GMLAN serial data circuit. The radio then displays the desired screen informationon the info display using the video data circuits.

Antenna System

Multi-Band Antenna

The multi-band antenna is located on the roof of the vehicle. This type of antennamay be used with the AM/FM radio, but is primarily for cellular and GPS signals, ifthe vehicle has these features. Keep this antenna clear of snow and ice build up forclear reception. If the vehicle has a sunroof, the performance of the system may beaffected if the sunroof is open. Loading items onto the roof of the vehicle can interferewith the performanceof the system, ensure the multi-band antenna is not obstructed.

Active Antenna

The active antenna system uses an integral antenna applied as an appliqué to the rearglass. The antenna module receives both AM and FM signals from the rear glass antenna.The antenna is part of the rear window and looks similar to the defogger grid. Oneantenna receives AM signals while the other antenna receives FM signals. Any damageto the antenna requires replacing the glass.

The radio antenna module is enabled when the radio is turned on. The radio providesbattery voltage to the antenna module using the center conductor of the antenna coaxialcable. When a 12-V signal is seen by the module on the center conductor of the antennacoax, both AM and FM signals are amplified.

Radio Reception

AM/FM Radio Signal

The radio signal is sent from a broadcast station and is then received by an antenna.The strength of the signal received depends on the following:

The power output (wattage) of the broadcasting stationThe location of the vehicle (or receiver) relative to the broadcast tower.Height of the broadcast antennaHeight of the receiving antennaObstacles between the tower and the receiverAtmospheric conditionsWhat band (AM or FM) the station is broadcastingType of antenna and the ground plane

Digital Radio Receiver (If equipped)

The XM satellite receiver is integrated into the radio. XM satellite radio providesdigital radio reception. The XM signal is broadcast from two satellites and, wherenecessary, terrestrial repeaters. The high power satellites allow the antenna to receivethe XM signal even when foliage and other partial obstructions block the antennasview of the satellite. Terrestrial repeaters are used in dense urban areas. Theserepeaters will receivethe satellite signal and re-broadcast them at much higher power levels in order toensure reception in areas with densely packed tall buildings. A service fee is requiredin order to receive the XM service.

Radio Data System (RDS)

The RDS feature is available only on FM stations that broadcast RDS information.This system relies upon receiving specific information from these stations and onlyworks when the information is available. While the radio is tuned to an FM-RDS station,the station name or call letters display. RDS data is carried in what is known asa "subcarrier". A subcarrier is a frequency that the FM broadcaster is authorizedto use to send datathat is not audible in the main audio program.

RDS functions will only work with FM broadcast stations that are broadcasting RDSdata. Not all FM Broadcast stations broadcast RDS data or offer all of the RDS services.

The information displayed is dependent upon the information broadcast by the particularstation. The information may vary greatly between stations. RDS functions may notwork properly when reception is weak, reception is of poor quality, or RDS is notimplemented properly by the FM Broadcaster. In some cases, a radio station broadcastingincorrect information may cause the RDS features of the radio to appear to work improperly.

With RDS, the radio can do the following:

Display text information such as: station identification, type of programming, andgeneral information (artist and song title, station messages, call in phone numbers,etc.).Seek to stations broadcasting the selected type of programmingReceive announcements concerning local and national emergenciesReceive alert warnings of local or national emergencies. When an alert announcementcomes on the current radio station, ALERT! displays. You will hear the announcement,even if the volume is low or a CD is playing. If a CD is playing, play stops duringthe announcement. Alert announcements cannot be turned off. ALERT! is not affectedby tests of the emergency broadcast system. This feature is not supported by all RDSstations.Speaker Operation

Speakers turn electrical energy into mechanical energy to move air, using a permanentmagnet and an electromagnet. The electromagnet is energized when the radio or amplifier(if equipped) delivers current to the voice coil on the speaker. The voice coil willform a north and south pole that will cause the voice coil and the speaker cone tomove in relation to the permanent magnet. The current delivered to the speaker israpidly changingalternating current (A/C). This causes the speaker cone to move in two directionsproducing sound.

Audio Amplifier

Amplifier Interface

A fused battery voltage circuit provides the main amplifier power. A switched 12-Voutput from the radio is used to control the power - state of the amplifier. To respondquickly to audio input and control signals, the amplifier is ON in all vehicle powermodes except OFF and CRANK Request. The internal amplifier bridges are fully poweredand unmuted when the amplifier receives the switched 12-V input.

Amplifier Operation

The purpose of the amplifier is to increase the power of a voltage or current signal.The output signal of an amplifier may consist of the same frequencies as the inputsignal or it may consist of only a portion of the frequencies as in the case of asubwoofer or midrange speaker. The radio creates a low level stereo audio output signal,which is sent at the user-defined volume level to the audio amplifier. The audio amplifieramplifiesthe signal and sends it to the appropriate speakers. Each of the audio output channelcircuits (+) and (-), from the amplifier have a DC bias voltage that is approximatelyone half of battery voltage. The audio being played on the system is produced by avarying AC voltage that is centered around the DC bias voltage on the same circuit.The AC voltage is what causes the speaker cone to move and produce sound. The frequency(Hz) of the AC voltagesignal is directly related to the frequency of the input (audio source playing) tothe audio system. Both the DC bias voltage and the AC voltage signals are needed forthe audio system to properly produce sound.

Theft Deterrent

The radio theft deterrent system is intended to disable or limit radio functionalityif incorrect vehicle information is received by the radio. The radio disables functionalityif the VIN information received by the radio does not match the VIN information thathas been learned by the radio. The radio receives this information via serial data.A possible cause of incorrect VIN info could be the radio was originally installedin anothervehicle.

The radio has the following theft operating modes as part of the theft deterrent system:

Normal Mode: The radio has learned a correct VIN sequence and the VIN informationreceived via serial data matches the learned VIN sequence. In this mode the radiohas full functionality.No VIN Mode: The radio has not received or learned a correct VIN sequence. In thismode the radio has limited functionality.Theft Detected Mode: The radio has learned a correct VIN sequence and the VIN informationreceived via serial data does NOT match the learned VIN sequence. In this mode theradio may be disabled or have limited functionality. The radio display will indicatethat theft protection is active.Auxiliary Audio Input Jack (If equipped)

The infotainment system may have a 3.5mm (1/8 in.) auxiliary audio input jack locatedin the center console. The auxiliary audio input jack may interface directly withthe radio, or be connected to the infotainment system via a Multimedia Player InterfaceModule. When a portable audio playback device is connected to the auxiliary jack,an internal switch detects the connection and the radio will switch to AUX as theaudio source. Audiosignals from the device are sent to the radio from the auxiliary jack via the left,right, and common audio signal circuits.

When a device is first connected to the 3.5mm (1/8 in.) input jack the infotainmentsystem automatically switches to that device. If an auxiliary device has already beenconnected, press the AUX or CD/AUX button to select the device.Playback of an audio device that is connected to the 3.5mm jack can only be controlledusing the controls on the device.The volume control on the device may need to be adjusted to ensure sufficient playbackvolume through the infotainment system.USB Port (If Equipped)

The infotainment system may have a USB connector located in the center console. TheUSB connector may interface directly with the radio, or be connected to the infotainmentsystem via a Multimedia Player Interface Module. The USB connector supports both USBstandards 1.1 and 2.0.

USB Supported Devices:

USB Flash Sticks (Thumb Drives)Portable USB Hard DrivesPortable Digital Media Players ( iPOD®, ZUNE®, etc.)

Depending on the USB device, some devices may not be recognized, or some features/functionsmay not be able to be controlled with the radio controls. USB HUB devices are notsupported.

Multimedia Player Interface Module (MPIM) (If Equipped)

The vehicle may be equipped with a Multimedia Player Interface Module. This modulecan receive signals via the USB connector, the auxiliary audio input jack, or a Bluetooth®connection. This module receives the incoming signals , then sends the signals asanalog audio inputs to the radio.

To allow the radio controls to be used to control portable media devices (USB, Bluetooth,iPOD®, ZUNE®, etc); the MPIM translates the USB signals to GMLAN signals to allowthe bi-directional communication between the radio and the device. Depending on thedevice, some devices may not be recognized, or some features/functions may not beable to be controlled with the radio controls. USB HUB devices are not supported.

Active Noise Cancellation (If equipped)

The Active Noise Cancellation (ANC) system is a method used to reduce the perceptionof certain undesirable sounds generated by the engine into the vehicle cabin. Thesystems uses microphone and engine speed signals, software integrated into the amplifier,and the vehicle speakers to determine and generate the correct frequencies neededto achieve the desired reduction.

For additional information on ANC, refer toActive Noise Cancellation Description and Operation

OnStar-® (If equipped)

When OnStar is activated, a serial data message is sent to the radio that activatesa software program. When the software begins its process, the fade goes to the front,Bass and Treble are set to the mid range, the outputs are mono, and the audio sourceis OnStar. OnStar takes priority over any other audio source. All of these actionsare preset values stored in the radio.

For additional OnStar information, refer toOnStar Description and Operation.

Steering Wheel Controls (If equipped)

Some audio functions are available using the steering wheel controls. The steeringwheel controls duplicate the function of the primary controls available on the radio.

For additional information on steering wheel controls, refer toSteering Wheel Controls Description and Operation.

Auto Volume Control

With auto volume control, the audio system will adjust automatically to make up forroad and wind noise as you drive, by increasing the volume as vehicle speed increases.To use auto volume control, set the volume at the desired level, and then select eitherLow, Medium, or High. To turn auto volume control off, select the Off screen button.