Sometimes while driving, the ABS light decides to come on/off. Sometimes it won't come on at all, sometimes it stays on for a while and sometimes it just goes off while driving. This was diagnosed to be a left rear speed sensor, but even after getting that changed, no difference, so I decided to get the ABS ring changed, however, still no difference. The ABS light just seems to come on and go off whenever it feels like it, as well as "ESP Defective" and "Service Brake! Visit Workshop!". Any idea what it could be? Been hooked up to many diagnostic machines, and they still say left rear speed sensor as current while the ABS light is on. All the wiring has been checked too and it all seems to be fine.