The light will only come on when the sensors go to ground and complete the circuit (meaning they make contact with the rotors). If the wires are broken, the circuit will never be complete and you will never see a light.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.