If you have a HARM on board and your HARM OVRD is not Boxed and your HARM detects a possible leathal threat the HARM will be first priority weapon and will launch in self protect mode on the pickle.
However if you have a HARM on board and do not want the HARM to override any weapon, make sure HARM OVRD is boxed. Now you will get the PLBK indication if the HARM detects a threat, but the priority will still be on the selected weapon.