Accessories and Optional Equipment: Description and Operation

AUDIO SYSTEM
Some of the radios are on the PCI Bus system. The PCI Bus inputs into the radio are used for VF dimming, remote steering wheel controls and cabin EQ preference. PCI Bus outputs from the radio are used for the cabin EQ preference.

The radios have the capability of containing multiple vehicle unique equalization curves (cabin EQ preferences) within the radio. These curves will reside in the radio s flash memory. The radio is capable of storing up to 20 unique equalization curves. The latent curves can be selected via the Front Control Module transmitting a PCI Bus message to the radio in response to a radio request for equalization message. Upon receipt of a valid equalization select message response, the radio will switch to output the corresponding equalization curve.

All the radios are capable of displaying faults and allowing certain actuation tests through the use of the DRBIII(R). When attempting to perform PCI Bus diagnostics, the first step is to identify the radio in use in the vehicle.

When trouble shooting output shorts or "output" error messages, the following applies:

On radios without an external amplifier, the term output refers to the path between the radio and the speaker. This type of circuit can be monitored all the way through the speaker connections by the radio assembly. When the radio displays a shorted output DTC with this type of system, the speaker, radio, or wiring could be at fault.

On radios with an external amplifier, the term "output" refers to the circuit between the radio connector and the amplifier. The radio is capable of monitoring only this portion and can tell nothing about the circuit between the amplifier and the speakers. Consequently, a shorted output DTC on this type of system would only refer to this circuit. A faulty speaker could not cause this DTC.

NAVIGATION RADIO
The optional navigation radio system receives GPS signals from up to eight satellites to display the position and direction of the vehicle. Map information is supplied through a DVD-ROM. An electronic gyrosensor and the vehicle s speed sensor enable the system to display the present vehicle position even in locations where GPS signals may be blocked.

When a destination is selected, the navigation system uses information from the map to quickly calculate a route. As the vehicle is driven along the chosen route, the operator is guided with pictorial displays and voice prompts. For complete operating instructions, refer to the manual included with 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 a voltage drop to be seen by the BCM and it sends a specific message to the radio on the PCI Bus circuit. The radio then responses 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 CHANGER
The new in-dash CD Changer is designed to fit into the existing cubby bin in the center stack. This new cartridge-less CD Changer is controlled by your radio, and allows you to individually load up to four discs at a time. However, due to its compact design, the CD 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 features of the CD Changer with the exception of the CD load and eject functions, which are controlled by buttons located on the front of the CD Changer. The radio also supplies the power, ground, PCI Bus, left and right speaker output through a single DIN 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 Changer information on the radio display.

The CD Changer contains a Load/Eject button and an indicator light for each of the four disc positions. The individual light indicates whether a CD is currently loaded in that particular chamber of the CD 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.

DVD/CD CHANGER
The DVD/CD Changer (if equipped) is located in the instrument panel below the radio. The DVD/CD Changer can hold one DVD at a time. Three RCA jacks on the front of the unit will allow the use of MP3 players, video systems or camcorders.