I also wanted to add some additional information for anyone else looking to do their own install.
I made up my own 'T harnesses'. i.e. OEM harness plugs into custom T harness, custom T harness has some wires tapped in the middle, and the other end plugs back into your amp. Makes things 100% reversible with no damage or modification to any OEM wiring.
Suitable for someone needing subwoofer signals, front door speaker/woofer signals, remote wire, grounds, constant 12v etc for aftermarket line out converters.
Here is the info, again for this particular year range and plug type:
Standard Toyota 6+10 pin plugs.
I bought male ends to plug into amp, and female ends to plug into the factory amplifier wiring (and then connect them together to make your custom harness and tee off whatever signals you need)
I didnt need to use plug A, but plug B comes in handy as its a speaker plug and used to Tee off subwoofer signal wires
The only reservation I have with a pre-made 'Plug A' , is that the OEM Toyota 12v harness wires appear to be a thicker gauge than the rest of the harnesses for the 12v wires going into the amp.
The aftermarket pre-made 'Plug A' 6 pin (where 4 wires are used) would not be to my liking as a 'pass-through'
If I had to actually tap into 'Plug A' (which I dont in my setup), I would have either de-pinned the aftermarket harnesses to put replace with a thicker gauge to match OEM, or just buy a 'crimp it yourself' solution for this plug and make one from scratch.
The pre-made aftermarket stuff seem to be fine as a pass-through in terms of wiring gauge for plugs B+C (speaker wires). Visually they appear to be the same gauge and copper wires.
Male end: https://www.aliexpress.com/item/32670180830.html
Female end: https://www.aliexpress.com/item/1245505321.html
One of many 12 pin plug combinations. Another speaker plug per the above diagram. This one is commonly referred to as the "5+7" plug for Toyota.
This harness already had both male and female ends, and a 'Tee off' already done for you into a 3rd plug (which you could cut off). Plugs into amp wiring, and other end into the amp.
Good to take front door woofer signals etc.
Another 12 pin. Mainly data signal based stuff
Only real thing to 'tee' off here, is a remote wire (That is, if you dont want to run a fresh one from your fuse box, or use a 'remote turn on' feature from many modern line out converters)
I couldnt find anything pre-made, but this is a male and female end, with crimp pins.
You can get this from Digikey, Mouser etc.
Female side part 1473407-1 . Pins part 1674742-1
Male side, part 1318774-1 . Pins part 1123343-1