I have a 2008 Trailblazer LS equipped with a towing package. I purchase an aftermarket controller which has four wires-white (for ground/negative terminal), blue (for electric trailer brakes), black ( for positive terminal from battery) and red ( cold wire for brake lights). My vehicle owners manual indicates wiring for electric brakes is located under the instrument panel. I have located an unused Delphi connector with 9 wires of various colors. What wire colors do I use for this model vehicle that correspond to above colors on the controller?