Thanks for your indications.Can you trace which pipe from the ABS unit goes to the sticking brake caliper and when it is sticking see if slackening that brake union at the ABS unit frees the brake off?
I've been making some trips and giving some sudden brake pedal pressing in little periods and it looks the problem has been solved .
Perhaps the valve in the AbS unit has been unoocked doing this.
If it goes again,I have to try what you say.
Thanks a lot