The following control modules are involved in the radio function:
The Control Display (CD) and Central Information Display (CID) are separate components. The Control Display (CD) with the Central Information Display (CID) and the Controller (CON) contains the operation and display elements for the vehicle electronics, with the exception of the ADP functions.
The Control Display (CD) co-ordinates the function requests from the system and assigns them to the individual functions. For the Control Display (CD), the following is displayed on the tester:
The Central Information Display (CID) is the display unit. For the Central Information Display (CID), the following is displayed on the tester:
The Controller (CON) is the control element for the Control Display (CD) with the display unit Central Information Display (CID). To run operating functions, the front Controller (CON) is folded out of the center armrest.
The Audio Display Panel (ADP) is the operation and display unit for the audio, video and TV functions. The Audio Display Panel (ADP) incorporates an LC display and control elements. Some control elements are firmly wired to the Audio System Controller (ASK). The remaining control elements and the LC display are connected across the data bus to the Control Display (CD) control module with display unit Central Information Display (CID).
The audio system controller (ASK) is a control module in the MOST network. The ASK is responsible for managing all audio signals.
The rear-window antenna is subdivided into a number of reception areas in order to improve reception. The distribution to right and left has been made according to the arrangement of the antenna amplifiers.
The MOST (Media Oriented Systems Transport) bus links the audio, video and navigation systems. Information relating to function requests is transmitted to the relevant control modules by means of MOST bus messages.
A car radio is constantly subjected to changing reception conditions. The rear-window antenna has been divided into the following functional areas to improve reception:
The HF signals received and filtered are amplified and converted by the antenna tuner and fed onto the MOST bus as LF signals. The audio system controller (ASK) prepares this data for sound output.
The antenna tuner is a control module for the radio and TV reception functions.
The antenna tuner has a separate power supply.
The following are connected to the antenna diversity unit:
The antenna diversity unit selects the best antenna circuit by the following process:
The audio signals include the gong functions (PDC, CC, double gong, hourly gong and continuous gong), navigation announcements and telephone. The audio system controller (ASK) mutes signals at the loudspeaker to highlight other signals. (Example: radio ”Mute” function when a telephone call is accepted.)
The Control Display (CD) coordinates the function requests from the system and assigns them to the relevant functions.
The Control Display (CD) is the only control module that knows the function (listen to radio) set in the system. If the volume is to be increased (function request), the Control Display (CD) sends a message to that effect to the ASK/amplifier. This telegram also contains the information indicating to which audio source the volume adjustment applies. Infotainment audio output is always a certain amount louder than the entertainment sources.
The best way to check FM reception is to drive in a circle. The antenna diversity unit connects the antenna with the best reception to the antenna tuner.
Connect the vehicle to the diagnostic system and select the control-module functions.