cattledog:
Power the sensor with 5v/gnd from the Arduino. Connect the third signal wire to pin D2 of the Arduino. Run the program and bring a chunk of steel to and away from the sensor. Can you see the led go on an off or the serial output switch from 1 and 0?
I carried out the example, but no change in LED blinking when I passed a screw driver more times for the sensor.
I beeped all the wires with my multimeter, so it is connected. Altough I am not 100% sure about the wiring, I think yellow has to be 5V, black to ground and grey to signal. Should I try to change the 5V and signal wires or could this damage the sensor.
Beside this I tried the example with a press button and that worked fine.
cattledog:
If you don't see a response, the sensor may not be working at 5v. What voltage did you find on the A prong which powers the sensor?
As I said in a previous post, I did'nt measure any change but am not 100% sure where I have to place the second probe from the multimeter? Normally you measure voltage parallel to a wire, but I only have one pin which is sticking out of a connector outside the dyno sensor box.