I just fixed this problem on my clubsport pedals.
The potentiometer was dirty, so I cleaned it with electrical contact cleaner.
If you look at the back of the potentiometer, there's a small notch on the outside edge, and you can spray the cleaner in there. Turn the dial a full turn and back while you're spraying it, work it a little, and it should work just like new. I had to repeat this several times before the problem was completely fixed.
I'm thrilled. I signed up for this forum just to pass along the info.
(oh, the deadzone update appeared to do nothing for my pedals. After completing the update, the problem was exactly the same as before. But now that I cleaned the potentiometer, the deadzone is very apparent and works well.)
the theory:
the circuitry of the pedal works backwards from how you would think it would (atleast from what I assumed). If you disconnect the load cell from the circuitry, (it has a red, white, and black wire), the pedal reads full brake force. This indicates to me that the brake is essentially a switch which is by default in the "on" position, and it is in the "off" position when fully depressed (open circuit/ no connection). To me this means that when you press the brake pedal, you are creating progressively more and more resistance until the circuit is broken. And if this is true, a false brake input will result if there is any unintended resistance in any part of the brake circuit. In other words, if the potentiometer is dirty, it creates more resistance than the circuit is designed for, making the game system think the pedal is being pressed when it isn't.
The deadzone fix provided by Fanatec works for some people because it compensates for a small amount of unintended resistance within the brake circuit. But it will only fix the problem if the extra resistance from the potentiometer is less than the amount the deadzone is meant to compensate for.
I doubt that the new load cell is a permanent fix. My guess is the resistance of the new load cell might be slightly less than the old one, giving you a little headroom and hiding the real problem. If it was the same problem where GT5 shows a very small amount of phantom brake input, I'm fairly certain that most cases of this are caused by the potentiometer.
And it's all happening because the pedals are designed to be insanely sensitive, which is why we bought the wheels in the first place....