I'm trying to measure/test the square wave output of an active wheel speed sensor from a jeep wrangler for a project I'm working on. I do not have access to the actual vehicle just the sensor itself and so I was using a test rig with the tone ring attached to a lathe and bringing the sensor as close as possible to the teeth of the tone ring. At the moment I am having no luck in getting any type of signal from the sensor itself. I wasn't sure initially whether the sensor was active or passive so I tried first without applying power to the sensor and had the oscilloscope hooked up over the two pins of the sensor. No signal appeared so I assumed it must be an active sensor. I then did the same setup but this time connecting the positive pin of the sensor (I measured this on the vehicle before hand and saw it was at ~2V) to my power supply set at 2V and the other pin of the sensor to ground and then measuring over that. Again, no signal. I then read that sometimes these sensors modulate current instead of voltage so I attempted to add a shunt resistor and measure over that to no avail. I assume I am setting up my oscilloscope or power supply incorrectly since the secondary pin on the sensor is usually refereed to as the "signal pin" and not ground pin. I am almost certain the sensor I have isn't damaged as I have two of them and can't get a signal off of either.
My next train of thought was to incorporate the sensor into a wheatstone bridge and try to measure the signal that way. I haven't yet tried this but I figured I would post here first to see if anyone has a better idea of how to use these things or provide insight on how a vehicles ABS ECU does the measurement. I.e. Has anyone measured wheel speed with these outside of a vehicle? If so how did you do it?