Radio wiring harness?

[aeroquality]

I am planning a stereo, speaker upgrade on my 2015 Bay Star Sport. It came with a Jensen and two small speakers in the ceiling. I found the unit has a thick wiring harness. It has labels wires for multiple speakers. It is fed through the dash behind the drivers dash. Not sure how far it goes, or at what the point the unused speaker wires terminate. Looking for any insight on this harness.

[BFlinn181]

I wouldn't worry about where the unused wired end, just cut and splice new wires to your new speakers where ever it's convenient under the dash. If you upgrade the speakers in the roof, hooking new speakers into the present wires is all that's needed, unless you're planning to add an amplifier and need heavier wires.

My RV had 4 speakers wired, two in the roof overhead and two more in the bedroom. I added 2 speakers under the dashboard and a DPDT switch in the dash to shut off the bedroom speakers and switch to the under dash and overhead ones. It makes it better for travel and listening in the front half when parked too.