From what I can find the 05 Colorado does not have a harness for the brake controller and has to be hard wired. I have pretty much decided on a proportional controller over a time delayed one. If anyone has any feedback on this I would be very intrested to hear it. I have found several diffrent controllers on line and from what I can tell any of them should work but when I plug in my truck and year modal in the search box it narrows down the selection to just a few. Since the controller has to be hard wired I think any of the controllers will work but I am not sure. If anyone can help me out with this I would appreciate it.