I just purchased a 2008 Grand Prix GXP and it has every option except engine block heater (don't care) and navigation. I ordered a factory ACDelco GPS/Navigation antenna and I will install it tomorrow in the factory location. I know I need to have the nav unit unlocked but I have a couple of questions.
Can anyone tell me (without guessing) what the 4th electrical plug is on the back of the nav unit (not counting the radio antenna port)? Port 1 and 2 are the factory radio plugins, port 3 is for the nav antenna and port 4 is for??
Once I install the nav unit and plug in the (3) know plugs will I need to install anything else to make the nav work as intended from the factory?
Thanks for your help.
