Right update! Checked all sensors and they are all close to 1ohm. Think the N/S/F has been the culprit.Every time the lights come on disconecting and re-connecting seems to re-set the system. What I'm, confused about now is as follows: From reading all the different threads about brakes, the system appears to send a signal when the vehicle first moves away when the speed reaches about 12-14 mph. At this speed I can hear what is best discribed as a "grinding" noise, thought it was supposed to be "clicking". Most of the time this is all that happens and the brakes work correctly. Occasionaly though, this "grinding" can be heard occuring at about 30 mph, and shortly after, the warning light will come on again. Quick disconnect and re-connect puts it all back to normal for a while. The question is, is it the sensor that's causing the problem or, because of the "grinding" thats occuring, elsewhere in the system? and what is it? Any ideas? Thanks in advance Nigel