Golf 1J: Auto Volume Changes Automatically (Solution)

The phone's volume is changing on its own.
Vehicle with radio navigation system.

Cause:
The phone volume, which is set in the volume settings, is occasionally reset to zero for reasons that are currently unknown. As a result, incoming calls are no longer detected.

Solution:
A separate speaker is required for telephone playback (accessory). The audio signal from the interface box (T18/7 and T18/16) must be connected directly to this speaker. The previous connection to the speaker switching relay is no longer used. When a call is received, the radio is muted via T8/2, and the voice playback occurs through the separate speaker. The telephone volume can only be adjusted on the mobile phone. Replacing the radio and/or telephone components will not make a difference!