Originally Posted by txpackers
Try just attaching the green parking brake wire from your Pioneer wiring harness to the black ground wire. That's what I did with my Kenwood system and it worked fine.
This is incorrect for a pioneer units.
And on to the correct way to do it with the AVH-"x"400 Series
It has changed on the newer ones AVH-"X"500
Although it is illegal to view while driving.
Pin 85 and 87 go to ground "black
wiring in pioneer harness
pin 30 goes to the light green
wire in the pioneer harness
pin 86 goes to the blue
stripe wire in the pioneer harness
Photo for reference