XJ40 ABS error light on?

My brother bought a rare 1989 XJR janspeed bi-turbo Jaguar from a guy as an MOT failure. The ABS warning light was on. When he got it home he opened the boot and removed the ABS controller relay. (Different year models have these relays in different places)

He then carefully prised open the relay and replaced the blade fuse within (8 amp, I think), put it back together and, hey presto the light went out!!

He still has this car and is about to completely restore it. I recall being taken for a drive in it so he could show off- going REALLY fast along country lanes, he said that it felt as though one or both front wheel bearings were worn, as the car felt a bit wobbly! Imagine our pleasure in finding out that the wheel nuts on all four wheels were not much more than finger tight!!