I'm attempting to figure out how the Vehicle Speed Sensor on my 2001 (AP1) Honda S2000 works. Unfortunately, I don't have access to a proper oscilliscope, just a multimeter.
I was hoping it would be a straight voltage (0 volts and you're not moving, voltage increases the faster you're going), but it appears to jump up to around 5 volts whenever I'm moving. This makes me think it must be a square wave and the speed is determined by the frequency (since it's just a coil spinning around somewhere and being read by a magnetosensor everytime it goes by).
Can anyone confirm this (or explain how it actually works), and is there a table somewhere where I can figure out what frequency corresponds to what speed?