I had to replace the L/R hub carrier and hub, so I had to remove the ABS wheel sensor. It was working fine but after reinstallation in the new hub carrier, I get several warning lights and the speedo does not work. How do you test the sensor? What is it, photo-diode, hall sensor?? Can it be checked with a vom, or is a scope necessary?

 

It's more likely the wire has an internal break due to flexing and age. But just check the resistance across the pins, it will probably be about 1000 ohm, but I'm not positive. Even with an ohmeter you can check the check that it fluctuates when you rotate the wheel.