2006 Chevy Factory Stereo Wiring

The two purple wires usually make up the pair for the right rear speakers. Here's the usual breakout for the wiring:

POWER WIRES

• Constant 12V / Memory Keep Alive: Yellow
• Accessory: Red
• Dimmer/illumination: Orange w/white stripe

GROUND WIRES

• Ground: black

SPEAKERS

• Right front speaker(+): Gray
• Right front speaker(-): Gray w/black stripe
• Left front speaker(+): White
• Left front speaker(-): White w/black stripe
• Right rear speaker(+): Purple
• Right rear speaker(-): Purple w/black stripe
• Left rear speaker(+): Green
• Left rear speaker(-): Green w/black stripe

AMPLIFIER AND ANTENNA WIRES

• Antenna: Blue
• Amplifier remote turn on: Blue w/white stripe

Those seem to match up very well with your adapter.

Here is a diagram I found for the 06 Colorado 4 or 5 cylinder engine

What you have there is part of a "Harness interface". It's for aftermarket stereos for newer vehicles that use a "data bus system" or a instead of a red ignition switch (acc) wire. You're missing the door chime part to complete the set. Without it idk how you're gonna bypass or get it to work. I found your post, albeit almost a year later, when I went to install a different stereo in my truck, 2006 Silverado 1500, and upon taking the old deck out I pulled out a scosche door chime wired in the harness lol. I was like wtf is this?!? At any rate, the pic I have here basically has the red on the door chime wired to the red on the aftermarket harness, the 2 purples go to the 1 purple on the chime (there must be some kind of relay/return signal) and the ground goes to both factory & stereo grounds, then the yellow also goes to both yellows.