2nd Gen Dash Speakers

I have a 2010 Tundra Double Cab non-JBL system. I’ve recently installed a new Pioneer deck along with a JL Audio 500/5 powering the factory speakers with the stock wiring harness. Also, I’m using a JL Audio 10w3v3 under the rear seat.

My question is what speakers are the dash speakers ran from?

I was playing around with the balance/fader on the receiver and noticed I have no sound when all to the front and when I use the rear I still hear music from the dash speakers.

I color coded all the wiring from the stock harness. I used speed wire.

Sounds good. But now I wonder if it could sound better. Shouldn’t the front/rear fader alter between front/rear speakers even with the stock wiring?