Hello,
I installed the pioneer AVH-X7800BT this week and used the Metra 70-1789 harness.
I replaced the stock amp so I can not help you there. Make sure your stereo is in standard mode and not network mode if available, but if you have front and rear fader then you are in standard mode.
Just search the forums and you will probably find your answer. Start with the sticky how to install aftermarket radio.