ZIP439
Thanks for your continued support, yes I did measure the voltage supply as per your suggestion and got positive 10v + readings to all four speed sensors. Also checked all reluctor rings for damage and cleaned away surface rust. I have a new brake light switch winging its way from Amazon US, (not available this side of the pond). I did have a moments success after switching the RCM to an old one I have when switching the ignition on, I did this to check if the traction control relay was working in it or not, (it was not), the ABS/BAS/ESP dash lights went off for a couple of seconds! This makes me suspect a cracked solder joint in one of the push in connectors to the RCM, when it stops raining, ( I do not have a garage), I will check them out. My new RCM is working with all relays active as they should be. I plan on replacing the tired relays in the old module with 40amp American Zettler new ones. Again I shall have to wait for some to arrive from supplier in the US.
By the way, unhooking the the large ABS fuse does not seem to make much difference to the stopping capability under heavy braking, neither does it prevent the stop lights working on my manual transmission model.