I'm also having this same issue. I have a 2011 Edge AWD with about 37,000 miles. My wife will be driving and it loses all power. So far she's been able to make it to the side of the road and the awd off message appears followed by the wrench light. I took it to the dealer and they found no problems or trouble codes. I was told the light had to be on in order to determine what the problem was. The problem with that is the vehicle has to be turned off and restarted to run again and that resets the light.
My daughter just got her driving permit and this becomes a safety issue for us.
