I just wanted to share this info since I found it hard to find myself. I have a 2006 Toyota Tundra SR5 DC and I am installing a new head unit and back up camera. I needed to know where the VSS (speed sensor) and reverse wire were located in order to correctly hook up the unit. Behind the factory head unit there were three wiring harnesses and one of them was not being used. That harness only had two wires in it and the connector was grey but the two wires are the reverse and the VSS wires. The reverse wire is the black and red wire and the VSS (speed sensor) is the orange and green wire. I hope that helps!