I'm afraid I don't have any answers to bucks 4x4 problem but I do have a 3 amigos problem that needs curing so, on the basis that all symptoms of a shared problem might be worth including in the same thread. Couple of months ago my 2000 disco td5 treated me to a very loud screech and an extremely hot N/S/R wheel. Removed the wheel and brake caliper to find a piece of rusty metal wedged between brake pad and disc (piece of rusted shim I think). Replaced rear calipers and pads and and all was well - except the 3 amigos appeared. I concluded that the excessive heat caused the insulation on the speed sensor to fail and ordered a replacement. Finally got round to fitting it yesterday but, disappointingly, the 3 amigos did not disappear as expected. I haven't tested any electrics yet and I don't have a hawkeye or other diagnostic (but I would bet that a fault shows up on the same wheel). The wheel hub shows no excessive wear and runs smoothly. Not sure where to go next!