Recently the 3 lights (trac off, service engine and ABS) all came on.

The sensor is a separate entity.

You could try Lightly sanding the sensors down cause of the rust build up from shitty weather, I've had this problem for over a year now and nothing seems to work other then pulling the 40A ABS fuse, but now I think it could just be the wheel speed sensor, but you may have needed the new harnasses because of where the sit at the back of the hub bearing assembly, which bends and turns and could have very well just been the the wires in the harness breaking, now tomorrow I'm going to lightly sand the hub assembly ABS connectors, if that it's the problem, it's most likely the ABS wire harness, if that's not he problem, it will most definitely be a wheel speed sensor, if you could let me know if these helped you that would be great, Cheers!