Do you have a multimeter? You will need one to find and fix this problem. The brake pedal sensor is a 3 wire device… B+, Signal and Ground. B+ is battery voltage, the signal should be 0.25 to about 4.75 volts as you press the pedal. It should be a good ground with essentially no resistance.
The P057C code is telling you the signal is low voltage output so suspect the wiring OR suspect a faulty Starter Generator Control Module.