VP500

The factory Nakamichi radio produced "err3" and this is the second time it happen so I rather purchase an aftermarket radio for my 2001 LX 470.

I researched a ton about the wiring harness but in the end came up with unanswered questions.

http://www.celiamania.com/wordpress/?p=181

Celica states that there is an aic-lan controller which sends all the functions to my factory amp.

So my question is do I just follow the wiring diagram and splice the correct cables coming from the factory radio harness or is there some type of interface I have to purchase that uses the pre-outs from the aftermarket headunit?

Thank you for your help!