Principles of Operation

Information and Entertainment System

Principles of Operation

NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).

Audio Control Module (ACM)

The Audio Control Module (ACM) can be operated with the ignition in RUN or ACC. The accessory delay feature allows the audio system to be operated for a preset period of time after the ignition is turned off and a front door has not been opened. The ACM sends AC voltage audio signals to the speakers or to the amplifier, depending on vehicle configuration. All ACMs except Base can produce their own DTCs, which can be communicated to the scan tool through the Medium Speed Controller Area Network (MS-CAN).

Navigation System

The vehicle navigation system guides the user to a pre-entered destination. No navigation map DVD is needed, as the map guidance information is stored in the ACM. The ACM calculates route information based on Global Positioning System (GPS) data. The GPS antenna tracks several satellites simultaneously. The ACM also uses vehicle speed and transmission gear selected signals received through the MS-CAN to detect vehicle speed and direction, resulting in more accurate navigation tracking.

The navigation display is part of the ACM. Either the touchscreen or the buttons on the ACM can be used to interact with the navigation system.

The compass heading on the ACM display is derived from the GPS antenna signal. There are no serviceable parts for the compass. If the vehicle is equipped with an overhead console, the compass display in the overhead console is derived from the compass module built-in to the overhead console.

Jukebox Feature

The navigation ACM contains a 10 Gigabyte on-board hard drive that is capable of storing music ripped (recorded) from a music disc. The music can be loaded into the jukebox by inserting a disc (in the proper format) and following the on-screen instructions to load the music into the ACM. The jukebox cannot rip MP3 discs.

AM/FM Antenna

A co-axial antenna cable connects the antenna to the ACM. Analog radio signals are sent to the ACM through the AM/FM antenna cable.

Global Positioning System (GPS) Antenna

For vehicles equipped with navigation, the GPS antenna receives information from satellites. The compass heading is also derived from the GPS signal.

Audio Input Jack

The audio input jack allows for a portable MP3 player to be connected to the vehicle audio system. When a portable MP3 player is connected, audio from the MP3 player can be played through the vehicle speakers.

Noise Suppression Equipment

The radio frequency suppression equipment reduces interference transmitted through the speakers by the engine ignition and electrical systems. When installing any new radio suppression equipment components, make sure that a good contact is made at all connections.

Network Communication

The following audio system components communicate via the MS-CAN:

- ACM
- Navigation ACM

The following messages are utilized by the audio system: