Scan gauge will read actual transmission temperature. It is a very good way to read trans temp.
The factory gauge goes to the middle of normal once the trans gets warmer than 50F. It then goes to yellow at 230F, and red at 250F (I think - I could be off a little on this number.)
Former Ford Automatic Transmission Engineer 1988 - 2007
Nobody has made MERCON since 2006. MERCON V replaced MERCON. Get over it.