The border point between Basel and Weil am Rhein was evacuated on Wednesday afternoon, causing long traffic tailbacks on the motorway, after police deemed a suitcase found in a coach to be suspicious, Freiburg police said in a statement.
A 200m perimeter was established around the area, before the suitcase was examined by a sniffer dog trained to detect bombs.
The owner of the bag was subsequently found and asked to open the suitcase. Upon doing so police discovered the cause of their suspicion: an electric hair shaver that had turned itself on in the bag.
The evacuation caused several kilometres of traffic jams on the A5, police said.
Customs points at Swiss borders remain on high alert following the terrorist attacks in Brussels last week.