You could certainly compare the same AC voltage reading spinning any of your other three wheels known to work, as further confirmation that you're doing it right. If that's it, then getting a hub with a working sensor will probably solve your problem. If it doesn't, remember you still wouldn't be immediately digging down to the skid unit. There's a decent amount of wiring to check on the way from the RR wheel to the skid unit.
Finally fixed the problem. It was the new hub assembly. The saying "I am not that rich to buy cheap things" once again proved itself to be true. I bought that one for $56 thinking I got a good deal, in fact bought myself an additional headache. How I fixed it: voltmeter method did not work. I did my research and found out that there are two types of sensors: passive, which generates electricity when spun and can be measured with voltmeter, and active, which NEEDS electricity to work and does not produce any itself. In order to test active sensor you need to make something like this: which is 12 volt battery (I used my jumper battery), LED and 220 ohm resistor. I couldn't find 220 ohm resistor so used my old mouse's 46 ohm one and its LED. Worked just fine. I learned how to do it from here. What it does is when a hub is spun the LED flickers. The good hub that I later bought from AutoZone near me for $110, flickered uniformly, the bad one flickered randomly. That's how I knew the bad one was indeed defective. Installed the good one and after I drove a little the lights went out by themselves, I did not have to clear them. Hope it stays like that.