Accessories and Optional Equipment: Description and Operation

An audio system is standard equipment. A rear seat video system is an available option. Two radio receivers are offered. The audio/video system uses an ignition switched source of battery current so that the system will only operate when the ignition switch is in the RUN or ACCESSORY/ACCESSORY DELAY positions.

The audio/video system includes the following components:
- Amplifier
- Antenna integral to the right quarter glass
- CD/DVD changer (if equipped)- Radio noise suppression components
- Radio receiver
- Speakers
- Video screen (if equipped)

Certain functions and features of the audio/video system rely upon resources shared with other electronic modules in the vehicle over the Programmable Communication Interface (PCI) bus network. The data bus network allows the sharing of sensor information. For diagnosis of these electronic modules or of the data bus network, the use of a DRB III(R) scan tool and the proper Diagnostic Procedures are recommended.

WARNING: THIS VEHICLE CONTAINS MERCURY ADDED DEVICES ADDED BY THE MANUFACTURER: REAR SEAT VIDEO DISPLAY. REMOVE DEVICES BEFORE VEHICLE DISPOSAL. UPON REMOVAL OF DEVICES, PLEASE REUSE, RECYCLE, OR DISPOSE OF AS HAZARDOUS WASTE.

Both the RAH and RBP radios are on the PCI Bus system. The audio output signal from the radios, on these central amplifier systems, is fixed at one volume level (level 25 for RAH and 26 for RBP). The actual volume, fade, balance, and tone adjustments are managed via messages sent over the PCI Bus from the radio to the amplifier which changes its speaker outputs to the corresponding settings. The amplifiers will also adjust volume based on speed messages received over the bus from the PCM. This keeps the sound level essentially constant relative to the interior noise level at all driving speeds.

Both the 6-channel base amplifier and the 8-channel surround sound amplifier perform digital signal processing and contain unique equalization curves in their memory. The specific audio source determines how the amplifier equalizes the individual channel outputs. Separate EQ's are provided for AM radio, FM radio, Tape, CD, and DVD video. There is a sixth EQ "slot" available for a TBD future input source. Audio signal EQ selection is based on bus messages received from the radio and Navigation unit. For example, DVD video is equalized for viewing video in the second and third row seats. Hands-free audio is processed using the AM radio EQ. Navigation audio is processed based on the current audio source EQ. The amplifier allows audio inputs from navigation and hands-free module to override whatever else might be playing at the time. The amplifier provides an independent output channels to each speaker location: 1) left front door, 2) right front door, 3) I/P center, 4) right rear door and 5) left rear door. On eight channel systems the amplifier provides two output (6 and 7) to a dual voice coil subwoofer. Both amplifiers contain diagnostic software allowing them to display Diagnostic Trouble Codes (DTCs) and perform certain diagnostic tests using the DRBIII(R). The tests available are the:
- Input Test - monitors input sources.
- PCI Amplifier Test - detect a checksum failure
- Identify EQ - displays the EQ currently being output by the amp (AM, FM, Tape, CD, DVD video).
- Continuous Tone Test - outputs a low and high note to each speaker (starts at the driver's door and proceeds clockwise around the vehicle).

REMOTE RADIO CONTROLS
These radios can be controlled via remote radio switches (optional). These switches are located on the back side of the steering wheel. They control mode, preset, seek up, seek down, volume up and volume down functions.

These functions are inputs to the Body Control Module and can be read with the DRBIII(R) under "body computer". The switches are a multiplexed signal to the BCM. The radio control MUX circuit is a 5 volt line that is pulled to ground through different value resistors built into the switches. This causes the BCM to see a voltage drop and it sends a specific message to the radio on the PCI Bus circuit. The radio then responds to the message.

This circuit is fairly simple to troubleshoot. The circuit must be complete from the switches in the steering wheel to the BCM. The ground must be complete so that the switches can cause the voltage drop for the BCM to see. The circuit passes through the clockspring so continuity through this devise must be verified.

CD/DVD CHANGER
The 6 disc In-dash CD/DVD Changer is designed to fit into the existing cubby bin in the center stack. This new cartridge-less CD/DVD Changer is controlled by your radio, and allows you to individually load up to 6 discs at a time. However, due to its compact design, the CD/DVD Changer can only carry out one operation at a time. For example, you can not load a new disc while playing another at the same time. Each operation happens sequentially.

The radio unit, installed with your system, provides control over all of the CD/DVD Changer features, except for the CD/DVD load function and the CD/DVD eject function. Buttons on the front of the CD/DVD Changer controls these two functions.

The radio also supplies the PCI Bus, left and right speaker output through a single cable. All features you would expect, such as Disc Up/Down, Track Up/Down, Random and Scan are controlled by the radio, which also displays all relevant CD/ DVD Changer information on the radio display.

The CD/DVD Changer contains a Load/Eject button and an indicator light for each of the 6 disc positions. The individual light indicates whether a CD/DVD is currently loaded in that particular chamber of the CD/DVD Changer. Pressing the individual Load/Eject button for a particular chamber will eject a disc currently present in that chamber. If the chamber is currently empty, actuating the Load/Eject button will position that chamber to receive and load a new disc in that chamber.

SATELLITE RADIO (SDARS)
To use the satellite radio, the radio must be in satellite mode. The satellite antenna must have an unobstructed view of the satellite. The vehicle must be outside to receive proper reception. Poor reception may be experienced in large down town areas where tall buildings are present. The satellite network is still under development, and this could be the cause of poor reception in certain areas. Use a known good system to verify network performance in these areas.

Once in satellite mode, the radio head is used to change stations. The Radio must be in Satellite mode to communicate to the Satellite Receiver Module with the DRBIII(R). The Radio head communicates to the Satellite Receiver Module via the PCI bus and the private Audio bus. The Audio bus functions just like the PCI bus, but its use is restricted to the Radio and the Satellite Receiver Module.

The Satellite Receiver Module processes signals it receives from the satellite antenna. That information is then sent to the Radio where it is processed and sent out to the speakers. The Satellite Receiver Module has the ability to detect and store fault code information, which may be retrieved with the DRBIII(R). Refer to additional information on the SDAR system and its related components.