GMC Repair: Brakes, gmc sierra, speed sensors

Question
Sorry the year is a 2000 GMC Sierra 4x4 the brakes work fine until I am almost stopped then I hear a noise that sounds like a motor and a vibration in the pedal very minor then the pedal goes soft? After making a sharp turn there seems to be no brakes at all?

Do you have a SC/Rambler if so father or son addition?

Thank You for your Time.

Answer
Hi
If the ABS is prematurely activating I would suspect one of the wheel speed sensors, or one of the wheels is locking up before the other wheels.  When the EBCM detects slip on one of the wheels, it will activate the ABS.

Let me know if any other help is needed.
Have a B paint scheme 69 SC/Rambler.