My 2005 ford F-150 will not reverse when engine is warm

Hello, lack of engagement in reverse or any gear is most often an indication of an internal transmission problem hydraulically or mechanically. There is a chance that an electrical concern has occurred, but it's less likely. Hands on testing using a Ford IDS diagnostic tester (or equivalent) is needed to monitor automatic transmission commands and responses. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops