I haven't taken my trunk apart yet but did fully disassemble my dash for the most part to get behind the radio as well as the kick panels/front side sills. Have had the door cards off to confirm and a pillars removed but not the rear door sills or rear seats taken off yet to investigate rear deck wiring yet. I am told there is wiring for the blank speaker pods (on base stereo) to reuse which I plan to for my rear component set of tweeters.
Here are my notes what I have documented:
Front right speaker can be found in front right kick panel on a gray connector plug
Green 16awg and green white stripe 16awg on gray plug pin 10 and 18
Front right Tweeter is found in a pillar
Green maybe 18awg and green white stripe 18awg wrapped in felt goes straight down a wire loom to the left and direct to mcu
Rear right speaker can be found in front right kick panel on a white connector plug
Red 16awg and red black stripe 16awg white plug pin 2 and 9
Front left speaker can be found in driver kick panel on a gray connector plug and also on a white plug (the gray controls more than just the speakers if you disconnect, the white is safer to disconnect as it's just the speaker wires)
Blue 16awg and blue white stripe 16awg pin 10 and 18
Front left Tweeter found in driver a pillar
Blue 18awg and blue white stripe 18awg runs down a plastic loom over the steering wheel and to the right toward mcu directly to the mcu
Rear left speaker is also found in driver kick panel
Gray 16awg and red white stripe 16awg
Here are the polarities I determined:
Rear left
Gray negative
red white positive
Rear right
Red black negative
Red solid positive
Front left
Blue negative
Blue white positive
Front right
Green negative
green white positive
Some more notes worth sharing. The main 4 door speaker wires are pretty thick 16awg in comparison to most of the rest of the wiring ran inside the cabin so it's actually pretty easy to find these wires once you pull off your panels.
Also in the driver kick panel there was a separate white plug that contained almost all the speaker wires you really need to tap into if your going to use some sort of high level to RCA converter or jl fix. The white plug in driver kick contains FL FR RL speakers, for some reason the RR speaker cable isn't there and it's found on a whole separate white plug in the passenger kick along with a cable for the rear trunk buzzer speaker.
Behind the mcu all 4 channels run to the gray plug beneath the heat sink. I tapped in there closest to the source and ran 4 16awg premium speaker cables to the left towards my hd radio unit just to the left of the steering column. On the opposite side of the hd radio there is a spot on the removable bracket that I understand the premium uhfs amp mounts to but with the base stereo it's empty and free to add 4 M6-1.0 x 10mm bolts to to secure a new audio device which I suggest. My jl fix 86 actually lines up just right with 2 of the holes so I just bought 2 stainless screws the size I mentioned and some blue threadlocker and enlarged 2 corner holes on the jl fix bracket to accommodate the thicker screw and viola it's mounted perfectly! My high level wires from the mcu go straight to that. I could have gotten the speaker signals from the white plug in the driver kick if I didn't want to take apart the dash to get behind my radio and ran another signal wire from the passenger kick inside the dash to my jl fix but since I went the whole way I took it direct from the radio to keep things clean and length of cables all the same. I tapped into my obd2 plug for 12v power and inserted a 1a fuse in line since that's all the jl fix requires. The obd2 is fuse protected at 5amps elsewhere in the car.
I never found where the tweeters were directly wired into behind the radio. Tried to tone and probe them but there was a lot of interference or electrical noise in most of the wiring or the toner I was using was a junk China tone and probe. But I did use a multimeter to check for continuity on both tweeter cables and found they are directly wired in to the main front speaker cables somehow, I assume they get spliced in somewhere hard to see or in a wire loom I didn't take apart. I just left them disconnected and dropped new speaker wire down the a pillar to each kick where my crossovers will go. The tesla tweeters have a resistor on each which must high pass crossover on the line itself.
Also worth noting with the base system. Just beyond the dash panel there is a metal painted grate pad you can remove and under that you will find 2 more 3" speaker blank openings (left and right) for the midrange speakers of the premium stereo. No wires were found there but it's easily accessible when the dash is all apart if you want to add more speakers to your car. I decided not to since I didn't want any sound reflecting off my windshield. I covered the opening with some sound deadener and acoustic foam to seal up the cavity. The center speaker is there right in the middle and very little room is there to remove the speaker, I didn't have the correct slim right angle torx tool to get it out and didn't want to scratch my fresh front windshield tint so I left it in place, I never found it's speaker wire combination or figured out how it was wired to the radio either. Left it connected for car blinker noise and other signals it sends out.
