I have a 2008 Toyota Highlander without the JBL system. Several questions,

Do I need a wire harness to install the Pioneer AVIC D3?

If I do need a harness, does it exist and where do I buy it?

The only wire harness I can find online is for JBL speakers. Here is the link:

http://www.autotoys.com/x/product.php?productid=10845

Will this harness work with the stock non-JBL speakers? I need help with installing this deck! Thank you.

Metra part number 70-1761

The part you posted will not work in your car because it's for integrating the radio into the factory JBL amplifier which you don't have. You need the wiring harness adapter in the link I provided..

Thank you. So what you are saying is that all I need to make the AVIC D3 work with my stock speakers is this wiring harness?

Does this wiring harness connect to the AVIC D3, or to the speakers?

I am completely new to installing these things, and I will probably pay a pro to do it. Thanks again.

It goes between the D3's wiring and the vehicle's factory radio plug/harness. You don't have to mess with any of the speaker wiring.

Thank you. You have been very helpful. One last thing, how can I be sure it will be compatible with the 2008 Highlander? The 2008 Highlander is not listed as being compatible with this harness on the website that sells it.

and you're second guessing him ?

go here http://www.metraonline.com/fit.aspx

ANd you can drill down through the car selction guide and see that you come to the EXACT harness HiFiSi looked up for you.