Why is the battery draining?

www.youtube.com/watch?v=KF1gijj03_0 -- check this out. It's a parasitic draw test. Also check all battery connections and negative connections to the frame and motor. All should be clean and tight.

When I put my feet on the brakes in my 1996 Ford F150 the dome light comes on sometime and my battery runs down what causes that at and what can I do to fix the problem

The later models (2011-2014) have a park detect switch in the shifter that goes bad, the switch may be diifferent but the process is the same to replace the switch. BTW, the item relists with a different item number and URL, it is easier to search through the items I have listed rather than to keep reposting here and making a nuisance of myself. https://www.ebay.com/sch/newyorkbuyer/m.html

The answer given by G is absolutely correct. Ford will charge a minimum $600 to replace the entire housing when its about a $17.00 fix