I have a Bluetooth Adapter MB Part No B6 788 000 fitted to the car. It works fine. My question is, does the adapter power down i.e not drain the battery when the car is 'asleep'? I ask because I recently had sudden battery drain after the car had stood for about 10 days. I tracked it down to a failed alarm sounder (shorted, corroded battery/ies in the unit) and have disconnected it. Fingers crossed, that was the problem. However, I went to the car the other day and when having opened the door but not put the key in the ignition, my mobile rang. I answered but found that I was connected to the car's audio system via the Bluetooth adapter. Either the adapter 'wakes' up when a Bluetooth signal is nearby or the unit is on all the time, hunting for Bluetooth signals and thus draining the battery, albeit, I guess only at a low rate. If you can clarify this for me I will be grateful.