I have a 16 king ranch with the Sony system. I have changed out just the sub it’s self and I’m going to build a new box for under the seat and working to get an amp all that but I’ve looked and looked. And im not sure how to go about adding a amp for the sub alone. I’ve seen there’s a harness hidden I’ve seen thousands of different t ways but I’d like to know the easiest and best way to add an amp for just the sub

 

I did a Sony upgrade on my 2015 platinum screw... this being said I found the easiest way to upgrade is to let a qualified sound shop do it for you ... no fuss no muss , money well spent !

 

Easiest way is to pay someone to do it,

Okay, kidding aside. easiest way I've found to add an aftermarket amplifier is:
Run power from battery
Run negative to chassis or back to battery
Run remote turn on to kick panel fuse box
Run input from stock connector where the oem amp connects to oem subwoofer.

Otherwise, you can also get the pac pro which connects behind the head unit and it'll supply RCA outputs to an amp and also has a remote turn on output. Then you just run power and ground. But this is a lot more work compared to the option above where you don't have to take out the head unit.

 

Mine didn’t have the oem sub harness but even if it did, I’ve read on here many guys couldn’t get it to work still. I bought a kicker and installed the KISL rca leads behind the headunit. That took all of maybe 30 minutes including running the rcas to the back. The power/ground/remote probably took another 45min to 1 hour, and that’s mainly cause getting the power cable through the firewall grommet is a PITA. So around 2 hours if you work alone and carefully like I do.