avic-d1 map screen lag, no vss

My installer forgot to install my VSS wire initially, and yes, the location was off.  The D1 only gets GPS positions every few seconds, not continuously.  Between updates, it uses the various sensors to estimate location as you move.  When it gets a GPS update, it notes the difference in its calculation and the GPS position, and updates a running table of correction factors.  Over time, accuracy increases significantly. 

When my installer finally connected the wire, I noticed that the tracking got much better.  You will also see that the algorithm switches from Simple to 3D Calibration.

You NEED the VSS wire.  You also need the Reverse Wire hooked up so it can tell if you are going backward.  Again, my installer forgot that wire too, so when I would back out of the driveway, the map showed me crashing in to my house.  And when GPS put me back on the road, the correction factors got all messed up.  When properly connected, the D1 is pretty accurate (of course, GPS is only accurate with a few meters, unless it ever implemented differential GPS).

Derek