Q: new pcm now theft light flashes and wont turn over on 2002 Ford Escape

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
got a used pcm with all the same numbers and installed now car wont turn over and the theft light flashes
(1) Answer
(2) Comments
You cannot just "swap" a processor. It must be programmed for multiple parameters...the most urgent one you have discovered. The PATS system (Passive Anti Theft System) requires programming keys to authenticate via the processor. If you change the processor - the keys are no longer recognized, and the car will not start. Restore your old PCM and your car should start. OR...have the keys programmed to function with the replacement unit.

I have to ask -- why would you need to replace a processor anyway? This is not a common need...
took car to the local ford dealer for a check engine light. they told me the pcm needed to be replaced because the codes could not be cleared. they could not flash the pcm
Well, if that is the case (I remain skepical! But I digress...), then the replacement PCM will need to be programmed to operate the parameters of the vehicle and most importantly to operate with your existing keys and transceiver.