I have my VSS wire hooked up. I have noticed that sometimes the nav map will freeze. When this happens, I have a decent signal and plenty of sats are showing (they are orange, is that good?). But, the speed pulse will read zero. After a while, the speed pulse will start counting and the map will start working again. Also during this time, the speedo in the vehicle dynamics will display a banner saying it is not available at this time. When the speed pulse starts working, the speedo will start working again.

 

If I disconnect the VSS wire, will the vehicle dynamics speedo still work?

The VSS (Vehicle Speed Sensor) wire takes a signal from the car to determine how fast the vehicle is moving. It uses that data, along with the results of the GPS math to figure out where on earth you are, and how fast you're traveling.

 

Without a connection to the VSS the nav system must rely entirely on the GPS math to figure out how fast you're traveling. The result is that you will lose some accuracy (GPS resolution is not as high as the VSS), and if you don't have a GPS signal, you won't get any tracking (tunnels, dense city buildings, etc.). You also won't get the vehicle dynamics speedo at all (you're seeing the result of that when you get the banner that says connection not available).

 

Something is wrong with your VSS connection, either you didn't get a good tap, or it's not actually your vehicles VSS. I would personally spend the time to fix the problem, but it depends on how accurate you want your system to be.