that button should turn off the traction control. if its lit up full time the abs is not working and neither is tc. you also get the abs light and brake light when the abs is not working.

if you cant find a bad wire to a hub or play in a hub would mean a bad hub and sensor being the cause. best to get it scanned at a shop for codes, or you can end up chasing your tail tossing money at it.

oh to ad, if when you first fire the car up if the abs light is not on asap, its likely a hub gone bad if it comes on with in the first few feet of driving. or while driving down the road.

if the light is on full time its likely a busted wire or bad connection.