the latest version of cruise control takes an input from the wheel sensors for TC as well as

Engine RPM
Gearbox output speed
in the event of it being an auto it also reads
Gear selection (cruise will engage in any gear thats capable of minimum cruise speed)
Gearbox input speed

all in the name of getting a smoother more effecient cruise control that doesnt hunt as much or power on as agressively.

if something doesnt line up on the new system it turns off.