Tow haul light on gear shift has started going off and on in my Ford Excursion?

[Desperate fish owner]

First had this problem one cool am last week. Makes vehicle feel like the transmission is not always engaging.
Today the over drive started messing up. It feels like you were pushing a clutch in and out. Last month the alternator went out and this caused transmission problems then unless the transmission can cause the alternator to go bad.