Tramission problem



truck starts driving good until it gets to 3rd then i must put on the overdrive for it to continue to drive, but it feels like it does not pass on 3rd


You need to be a little more specific. First of all, what year is your F-150??? Which engine is in your F-150?? Help me out here a little bit, from what I can understand from your post is your transmission will shift normally from 1-2. After that you lost me. What happens when the trans shifts from 2-3 and 3-4 ?? When you say you have to put on the overdrive, what do you mean?? Are you pushing the o/d off button to shut OFF the overdrive or are you pushing it to turn ON the overdrive??