Hi - I have a couple 3 botton information display units sitting around from a 2004 and 2005 Grand Prix. I would like to check them to see if they light up and what the mileage is. I do not have a car to plug them into. Both have the plug with 7 wires coming out the back. Does anyone know what I would hook positive and negative to in order to light up and see mileage. (what color wires). Any help is greatly appreciated.