It sounds like your brake calibration program is resetting. I suspect you have a grounding problem and your PCM looses its stored brake pedal calibration. I saw the Ford dealership hybrid tech almost drive my '05 FEH into a wall in the shop when he put it in drive. He had reprogrammed my PCM and forgot to do a brake pedal calibration before putting it in gear. I was on the passenger side when this happen and he was going to take me for a test drive. When he pushed the brake pedal down it went to the floor but he did get it stopped in time. When the PCM has reset, your required to start the vehicle and while in Park press down on the brake pedal to the full brake position so the PCM can calibrate the brake by wire pedal travel. The next time you press on the brake pedal, travel should be normal and calibrated. If your somehow loosing the calibration and the tech presses on the brake when it gets to the shop the brake travel calibration is normal and there will not be any codes. He also did a reprogram of the ABS that also could have caused a recalibration to be done.