I recieved this in the mail today and found it interesting and thought it might be helpful for anyone towing with a GM truck. It is in PDF format, scroll down to the 7th page it is in the blue section.
GM Trailer Brakes (http://www.ase.com/Content/ContentGroups/Service_Professionals/Tech_News_Downloads/Summer_Fall_2007/ase-technews-summer07-screen.pdf)
That's why Tekonsha lists two brake controller wiring cables. Only people trying to save $12 and change over a cable from the older to newer one without reading the directions on what it works on will have a problem.