Audio tuner control unit, component description - GF82.62-P-3132SX

MODEL 216.3, 221.0/1 except CODE (494) USA version up to Model Year 8

MODEL 216.3, 221.0/1 except CODE (498) Japan version up to Model Year 8

MODEL 216.3, 221.0/1 except CODE (810) Sound system up to Model Year 8

Illustrated on model 221

Fig 1: Identifying Audio Tuner Control Unit - Illustrated On Model 221

Courtesy of MERCEDES-BENZ USA

Location

The audio tuner control unit is located on a bracket in the luggage compartment on the left side wall behind the paneling.

Task

The audio tuner control unit is connected to the Media Oriented System Transport (MOST) and, with 2 radio receivers, represents the radio component and simultaneously the base version for the amplification of the audio signals. The 2 radio receivers ensure the reception of the country-specific radio stations. The audio tuner control unit administers all audio sources integrated in the vehicle (e.g. radio tuner) and processes their audio signals.

Design

The following components and interfaces are integrated in the audio tuner control unit:

2 radio receivers for reception of radio signals
MPEG decoder for processing of audio signals in DVD mode (audio or video DVD)
MOST interface

Function

The audio tuner control unit receives, depending upon the national version, high frequency (HF) signals for different frequency ranges (e.g. ultra-short wave (FM), medium wave (MW)). These HF signals are sent to the audio tuner control unit via a HF line directly from the rear window antenna amplifier module (A2/12). There, the incoming signals are processed, amplified and output via the speaker system.

Diagnosis

The audio tuner control unit has its own fault memory. All faults occurring during operation are stored there in a non-volatile memory. In the event of a request via STAR DIAGNOSIS, all diagnostic data are forwarded via the MOST to the COMAND controller unit (A40/3) which serves as the interface to the central CAN. The requested diagnostic data are forwarded to the central gateway control unit (N93) via the central CAN where they can be read out at the data link connector (X11/4).