
I have the same problem you described here.
At the begining i was thinking just was the hand brake switch or something turning on accidentally because it always happen when driving in a downhill where i have to brake faster than usual to stop the car.
But I just noticed it happens anyway when I need to brake fast and push hard the pad, then the red brake light turns on until I release the brake.
The user manual says something about ABS light and EBD (not sure

) braking systems, my picanto dont have ABS so I just think on something happening to the electronic brake distribution (EBD) though its frustrating not to have a workshop manual.
Regards...