Did you reuse your old sensors with the winter wheels or did you get aftermarket sensors? If the TPMS sensors are aftermarket you have to make sure they operate on the same frequency as the factory sensors. When doing a relearn are you selecting the relearn procedure on the DIC? You also have to put the tool very close to the sensor on each wheel to get them to work. Sometimes you have to find the right spot, but the horn will beep once for each sensor registered. I unusually do mine in this order LF, RF, LR, RR.