kkreit01, I figured out where the amp goes, just to the right of and at the top of, the emergency brake is a bit of steel frame, while it has several holes in it, it has two larger holes, with smaller slotted off them, like you see on a picture frame or wall clock. The Amp goes vertically up inside the dash with the screws in the silver mounting plate into the frame plate in those two holes and with the bump in the silver mounting place goes towards the BCM, so it blocks access to the BCM.
The AMP came from a wrecker. The wiring harness also came from a wrecker along with the two speakers in the headliner and the subwoofer under the rear seat. We had to replace my dash when we were rebuilding my truck as the dash got damaged, so we just happened to put in a dash that had the center speaker opening. I only needed the Instrument Panel harness from a truck with the alpine system in it. I stripped out the wires that are used for the amp, which includes the speaker wires and the canbus connector, and just made a harness out of what I stripped out. It goes from left to right across the whole dash and it fits... tight to work with in one area but the rest is easy.
Power wire is not shown correctly on the tech authority wiring diagram, but is actually PIN 5 on the inline-body/IP connector. I checked and the body side of that connector already had the pin in it for power and 12 volts coming from it, so I had no need to run any wires other than the wires going across the dash, and I will add the two speakers with grills and wires to the headliner later.
Basically there is a power wire, a ground, a canbus connector and all the rest is simply speaker wires (8 speaker wires go from the radio to the amp, and 22 come out of the amp, 2 pairs each for 10 speakers, but includes wires to support for a second subwoofer)
I just took some time and care taking the donor harness apart so I could put it back together with the various wires coming off the new harness is the same spots.
The hardest part of putting the harness in, was that there is a corner the harness has to turn just to the right of the cluster and to the left of the left vent. Slow going to get it thru that space, and smaller arms and hands would have made it easier to do. The only other hard part was getting the speaker wire to the center speaker hole on the dash, but a coat hanger curved the left and down came out to the right edge of the cluster where there is a u-channel... which looks to have the wire for the sun sensor on its right side. Tied on a string and pulled the center speaker right into place perfectly.
Now that I figured out how the amp mounts, I can go along and pull the old speaker pins from the left and right side of the existing instrument panel wiring (IP2 and IP3) and the radio connector, and then push in the new speaker wires into the same locations. I numbered all the pins for all the wires when I finished making the new harness.
Hopefully this weekend, I can get the wires put into the different connectors (IP side of IP, IP2, IP3 connectors and Radio) and get the amp mounted, then use Alpha to deal with the Amp and Surround Sound BCM settings, and I should have an 8-speaker system... until I get the chance to drop the headliner down enough to cut out and add the last two speakers.
All in all not really that hard to do, just spent a few hours and a few cuts getting the new harness across the dash (only one spot is a super tight squeeze). There is only pins to be changed on the IP side of the IP, IP2 and IP3 and the Radio Connector. A filed paper clip works great to pull the pins.
I got the amp, headliner speakers (and wire) and the door/dash alpine speakers and the Instrument Panel harness dirt cheap from a wrecker. In fact it came out of a 2014 not a 2015. They junk most of that stuff anyways, total cost was maybe $100.
Tried just the speakers alone at first, and that was a major improvement over the 6 speaker even without adding in the correct resistors. I know people like to upgrade the speakers but up here in Canada they want a fortune for good speakers. My way I got the full alpine like it came from the factory for $100 and some of my time, and a small amount of blood getting the harness in place. Works for me for now, and will sound even better down the road if I get better speakers for father's day some day.