How do I get my 2001Ford Expedition out of limp mode?

2001 Ford Expedition AC Recharge

Your shop is not honest or incompetent if they changed 3 transmissions and they only last a week. The front pump of the trans provides pressure. Limp mode is determined by the PCM is has no bearing here.

No way it works wit the processor change ignition key

Chances are there is a major problem with the transmission and what you actually have is a limp mode situation. The transmission can allow you to use 1st and 2nd gears to get you back home or to a garage without causing more damage.

Check engine light on , what code or codes are stored ? What engine ? 4.6 or 5.4 L LIMP mode usually has to do with one or two different thing's transmission problem or ETC electronic throttle control , yours does not have ETC . Plus that overdrive light is on indicates transmission problem . I would get a second opinion . Probably just a sensor or something like that . Could give you some better advice if knew what codes were stored in PCM

http://www.fixya.com/cars/t6628633-2001_ford_expedition_fuse_box

I got the following codes on 2005 ford expedition--p0300, p0301, p0316

sounds like limp mode thats what to computer does to protect your engine take it to a mechanic and get a code search done
then fix eithor the knock or the sensor malfunction

yes eventually it will slowly drain the battery

you will have to take it to get the tranny checked it is probably an electrical problem or the trans is stuck in limp home mode for some reason