Your crankshaft position sensor is small but mighty—without it, your engine can’t start or run right. Learning to test, diagnose, and interpret its signals can save hours of guesswork. From waveform ...

I have a Dodge that I suspect the VSS is going bad on. The speedometer jumps around sometimes, and is frequently off by 10mph or more. I called Dodge and they suggested replacing the VSS as a start.