Chevy express stereo replacement dilemma- where is the accessory wire?

[Samuel Blackwell]

I have been trying to wire up a new stereo for my 2005 express, and I have already cut the factory harness (oops). The problem I have is that I cannot find out where the accessory wire is, and consequently the new unit will not shut off with the car because it's only wired to the 12v constant. I gave tried to use a multimeter to find the accesory wire by having the key in the on position and seeing which wire reads 12v, but the only wire I get a reading for is the 12v constant wire. Anybody know which wire is the accessory wire? Or whether there even is one?

[MattM85]

Should be orange. Slighty thinner than the other two oranges that go to speakers. I have no idea why chevy felt the need to use orange so many times. Its confusing.  I had the same problem make sure you check your fuse for it.  That was my issue.

Edited June 2, 2022 by MattM85
Needed to add something