Had a Disco 2 in last week, Hill descent, ABS and TC lamps illuminated. Fault codes in the ABS modulator control unit pointed to shuttle valve failure.
Removed shuttle valves and clipped wiring. Made a new ground point at the AC bracket and reconnected routing new ground connection out of the bottom of the shuttle valve cover.
Result. 100% fix. Problem is that the internal pins of the ground connection go open circuit. (thanks to Landrover forum).