Land Rover Repair: abs lights, mud hill, discovery 2

Question
my 99 discovery 2 abs,tc lights come on sometimes but often go off when ignition is turned off and on again.The service people have done an abs pump kit and removed the error a few times. They say the module has a fault now which is big money but why if its faulty does all still work perfectly ?

Answer
The simple answer: it does not work perfectly.  You just don't notice the defect.

I think if you tried putting the system through all its moves - ABS on sand, traction control in mud, hill descent on a mountain - you would see one or more functions missing or wrong as a result of whatever's happening.

But if it's ok on the street you could certainly live with it till you have the funds for proper repair.