Does a used ecm need to be reprogrammed on a 2002 Mercury Sable?

I have been having problems with the heater going on high by itself and radio sometimes works and does not. had a few responses the other day and checked it out. found no problems or shorts. I was told all the signs point to the ecm. one day the radio would not shut off when the car was turned off and I pulled the # 17 fuse in the under the hood to shut the radio off. And the heater blows high and I cannot control it. Then sometimes everything works. right now I pulled the relay for the blower so the heat does not come up and the radio and clock light are not on.
Question; If I pick up a used ecm from a junked sable do I need to reprogram it.
Question; If I pick up a used ecm from a junked sable do I need to reprogram it.
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