I am not ready to upgrade yet, but I was looking over the wiring diagram for the radio and amp. I have several questions if someone could enlighten me.

The rear speakers have 4 wires to them. Are they powered, or passive?

There are four wires coming out of the radio, pin 3,4,5 6B. I assume these are non-amplified output channels? Is it listed somewhere what location they are for? Does an aftermarket unit need anything special to use the OEM amp without causing damage?

Last, why is the ABS controller invlolved?

Thanks, James