Doesn't have to be ABS. We have a 92 D1 that had pad wear sensors with no ABS. In the end I think with intermittent faults they got snipped. All I see now is the wires taped up. Maybe you have a sensor fault? Need to check if you have any thin electrical wired in the brake assy. If you do then you have some kind of sensor there and that may be at fault if your pads are in good nick and fluid is ok in brake master reservoir