After studying the circuit diagrams, I pulled the connector off of the underside of the fuse/relay box and disconnected the connector to the ABS controller. I found that one of the wires that takes a 12V supply to the ABS controller had a break in it. It had a splice somewhere between the 2 - which I thought was probably where the problem was. Of course it was somewhere in the wiring loom and I didn't have the time or inclination to get to it - so I ran a bypass wire along the route of the loom. That fixed all the error codes apart from the Front Right ABS sensor. I tested the continuity between it and the ABS connector and it was fine. I then replaced the sensor with one I had got from a breakers yard.......and once I got above 15mph......the yellow ABS light went out!! :-D
Argee's post in Location Of G100 Ground - Abs Problem was marked as the answer