I am putting together an aftermarket sub and amp in my 2016 king ranch, I am having trouble figuring out if I should tie the left and right speaker positive, and the left and right speaker negative together going into the LOC adapter. I didn't know if it would cause problems if I just used the left side positive a s negative and only have the left side of the rca cable going into the amp working, or if I could tie them together. My fear was feedback into the door speakers from the opposite side, or blowing something.

 

you’ll have better luck finding the answer over in the aftermarket stereo/audio sub forum here:

https://www.f150forum.com/f30/

 

King ranch must have sony system? think you have to go Zen Audio interface......not sure. LOC is not needed if amp can take HLI

 

You can also just make the Forscan changes to switch the signal to pre-amp and remove the dsp from the signal.
See line 101 in the Forscan common sheet.
You will also have to make the change to send the chimes to the IPC speaker, othwise they are ridiculously loud.