Tokyo stocks fell Tuesday morning as a stronger yen against the U.S. dollar weighed on exporters, while automakers were also hit by a safety test scandal that led them to halt some vehicle shipments. The 225-issue Nikkei Stock Average fell 173.78 points, or 0.45 percent, from Monday to 38,749.25. The broader Topix index was down 12.85 points, or 0.46 percent, at 2,785.22. The dollar traded in the lower 156 yen zone, losing ground overnight on the prospect of a narrowing gap between U.S. and Japanese interest rates after sluggish U.S. manufacturing data for May fueled expectations that the Fede…