Principles of Operation

PRINCIPLES OF OPERATION

Audio Control Module (ACM)
The audio control module (ACM) can be powered up when the key is in RUN, ACC, or START. The ACM provides audio signals to the speakers, thus producing sound. The ACM directs the audio signals to the speakers through separate positive and negative circuits for each of the 4 audio channels: LH front, RH front, LH rear, and RH rear. The ACM provides internal circuit protection for shorts to ground and shorts to battery.

Antenna - AM/FM
The antenna is a fixed mast antenna mounted on the exterior of the vehicle. The antenna receives both AM and FM radio waves. The audio signals are then sent to the ACM through the antenna cables.

Subwoofer
The subwoofer speaker is powered from a separate subwoofer amplifier. The enable/clip circuit carries out 2 functions: to turn the subwoofer amplifier on, and to indicate to the ACM when the subwoofer output distortion signal reaches an excessive level. The ACM then reduces (clips) the audio output signal to the subwoofer amplifier.

Rear Entertainment Module (RETM)
The rear entertainment module (RETM) receives power in RUN or ACC. The wake-up signal is sent to the RETM from the ACM through the medium speed controller area network (MS-CAN). When a video disc is inserted into the RETM and PLAY is pressed, an image is displayed on the screen and a stereo signal is transmitted to the ACM.

Satellite Audio
The satellite audio system consists of the satellite digital audio receiver system (SDARS) module, a satellite radio antenna, and an antenna cable. The satellite radio antenna receives digital audio signals and sends them to the SDARS module, where the signals are converted to analog and sent to the ACM. The wake-up signal for the SDARS module is sent from the ACM through the MS-CAN.

Navigation
The navigation module is integrated in the ACM and controls the operation and the interface between the user, the vehicle subsystems, and the external components. On-board diagnostics are available through the ACM self-test.

The vehicle navigation system guides the user to a pre-entered destination. A navigation map DVD stored in the navigation module sends route calculation data to the ACM. The ACM audibly and visually instructs the user of the maneuvers required to arrive at the destination entered.

In order to calculate the initial vehicle position, the global positioning system (GPS) antenna is used to track several available satellites simultaneously. A gyroscope, integral to the ACM, monitors the pitch and yaw of the vehicle created during cornering or turning. Vehicle speed and reverse signals are hardwired to the ACM and are used to increase the navigation system accuracy.

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.

Steering Wheel Controls
The steering wheel controls consist of a series of resistors. Each steering wheel control switch function corresponds with a specific resistance value within the switch. When a switch is pressed, the ACM monitors the change in reference voltage to determine the requested function.

Noise Suppression Equipment
The radio suppression equipment reduces interference transmitted through the speakers by the engine ignition and electrical systems.