Audio/Video/Entertainment/Connectivity (Service Information): Radio: Operation
The Security Gateway Module (SGW) is the Controller Area Network (CAN) gateway between the radio, telematics modules, Data Link Connector (DLC), and the other vehicle CAN modules. An SGW failure could prevent the radio from powering up, telematics module from communicating, or a scan tool from communicating with the vehicle. For additional information on the SGW. Refer to MODULE, SECURITY GATEWAY (SGW), DESCRIPTION .
Use of the MIT019 Multi-Media Tester may cause the radio screen to go blank.
The audio system components are designed to provide audio entertainment and information through the reception, tuning, and amplification of locally broadcast or satellite (if equipped) radio signals in both the Amplitude Modulating (AM) and Frequency Modulating (FM) commercial frequency ranges.
The SGW is in the audio and telematics systems to provide security against certain types of attacks and threats from the diagnostic scan tool, telematics, and entertainment buses, putting the rest of the vehicle's buses at risk of intrusion. The SGW lies electrically between the vehicle on one side, and the Data Link Connector (DLC), telematics, and entertainment systems on the other side. The primary function is to gate messages from one bus to another. The SGW monitors the B(+) Feed, switched ignition feed, CAN circuits, software, and hardware for any concerns.
The audio system components operate on battery current received through a fuse in the Body Control Module (BCM). The base radio receives an additional fused ignition RUN/START battery current feed from a fuse in the BCM.
The optional navigation radio system receives GPS signals from up to eight satellites to display the vehicle's position and direction. An electronic gyro-sensor 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.
The BCM receives the Steering Angle Sensor (SAS) inputs on vehicles equipped with the optional remote radio switches. The inputs are sent over the mux circuit from the remote radio switches to the SAS. The programming in the BCM allows it to process those inputs and send the proper messages to the radio receiver over the CAN-B network to control the radio volume up or down, station seek up or down, preset station advance, and mode advance functions.