ABS problem

Hi Can anyone help I have a 1984 Range rover classic with 91 modifications including ABS (carried out by a previous owner). After having ABS ECU analysed (dash light staying on) it showed 2 faults that will clear but return immediately. Faults are ETC valve normaly closed, open and ETC valve normaly open, closed. The wiring has been checked by an auto electrician with no faults found. The conections to the valve block have been cleaned and a good used valve block conected to see if if the fault was in the existing one, but that didn't clear the faults. On driving brakes work fine and did not fail on the MOT, but the light staying on did!!!!! Has anyone got any ideas as it has now run out of MOT and can't get it through untill ABS light goes off as should do.

Hi Just to update you as no one could help. the ABS has been taken off and back to the servo system.
ossieman