Speedometer Reads 50mph When Going 10mph

[Cool Mr Steve]

When I start rolling and my car hits maybe 3-4mph the speedometer jumps to about 40mph. When I hit about 20-25 it reads about 53 or so, and when I hit about 35-45 it will only raise to about 57-58. The needle isn't bouncing and I didn't do anything to provoke the problem. I got a flat rear tire today, but I doubt that caused it I don't seem to have a loose connection at the VSS. Does this sound like it could be the reed switch? The trip odometer doesn't seem to be affected (distance covered = distance read), so I wasn't thinking the VSS was the problem. Would I be incorrect in assuming that?

 

[freshlane]

I would have guessed VSS also. Check ground wires. My tach started acting crazy after I installed my safc to the same ground