How do I get this D3 NAV to work properly? I have a 03 Lincoln LS and the NAV is way off with the VSS unhooked. The NAV shows I am like 5 miles back from where I really am. I just installed this so Im not sure if Im mising a step here. I thought the NAV would work with the VSS unhooked but be off by a little, not 5-10 miles. Thanks.