For a Discovery LS swap to go well, it is a good idea to have most of the vehicle in good running order before starting the swap (minus the engine, of course). By this I mean that if there is other deferred maintenance on the vehicle, its best to get some of that out of the way before starting the swap. The LS swap will not fix other issues with the truck. One of the most common issues we hear about is colloquially referred to as the three amigos (indicated by the warming glow of the ABS / traction control / hill decent control lights).
There are typically two main causes for this: 1. a bad wheel speed sensor; 2. a shuttle valve electrical problem. A code reader that can access the ABS system computer (also known as the SLABS) can determine which fault is the source of your problem.
If the problem is a bad wheel speed sensor, the code reader should be able to tell which wheel(s) the problematic sensor is on. Replacing the sensor on that wheel can usually solve the problem. Occasionally, faulty wiring between the sensor and SLABS computer can be an issue, but in our experience, usually the sensor itself is to blame.
If the problem is a shuttle valve electrical problem, then there is a really great fix known as “Option B.” We can take absolute no credit for this fix, but its been around for a long time. Basically, the wiring in the shuttle valve in the brake system can go bad and the system gets a faulty signal - see above condition of wiring after a number of years. This fix involves running new external wiring to supplement the internal shuttle valve wiring. We always start with a fresh shuttle valve and then solder in the new wires as shown in this video:
The video sums it up pretty well. The ABS/TC/HDC system is a great asset when off-roading the Discovery. Our Discovery 2 LS swap kits keep the ABS/TC/HDC system working as it normally would, so its a great idea to make sure your system is in top shape before starting the LS swap.