PSE system, voice control module, or Tele Aid module failure can cause a lack of audio. These same modules can also cause dead battery conditions when they fail to "time out." Many electronic control modules are active even when the engine is off. If these modules stay active, they will drain the battery, which is why they have a timer built into the modules. The timer shuts down the modules after a preset amount of time (timing out). If a module does not time out, it will stay active and drain the battery.Google+
Car Problem Reports
Mercedes-Benz E320 PSE system/voice control/Tele Aid module failure may cause lack of audio/dead battery
Mercedes-Benz E320 Problem
Visitor, 2002 Mercedes-Benz E320, 81,000 mi
I just had multiple problems at the same time due to a low volt. battery. First, when vehicle was on reverse vibrated when I first pulled out the garage, and vibrated again when I shifted to drive. Second, the radio was non stop playing with everything off and the key was removed.Third, SOS malfunction. A little confused when everything happened at the same
time but all resolved when a new battery was replaced.