Have 2002 F-150. Have 2 OEM door fob remote transmitters and 1 of them still works but pretty beat up appearance wise. Bought 2 new aftermarket and have read instructions in owner's manual. My question is, if I just program the new ones will they be programmed with same codes as OEM or does the truck send out a completely new code and OEM and new ones all need to be programmed for all 4 to be functional?