My 2001 C240 w89k has started intermittently shutting down all electrical accesories including a/c, radio, lights, pretty much everything electrical except the engine keeps running. This will happen going down the road which is dangerous because lights, wipers etc dont work. My service guys cant find any fault codes and it only does it occasionally. If I turn the car off and restart it is ok for a while. Somebody suggested Rear SAM? Help!!!