Top Left - Trailer brake output level 0-999. Top Middle - MaxBrake logo. Top Right - Gain setting 0-100. Bottom - Error messages (Trailer Unplugged, Check Trailer Wiring, Sensor Unplugged, High Current, Dead Short). When a good trailer is connected the bar graph will track with your pedal. Bottom Right - Indicates how much current the trailer is drawing in Amps (+/- 1 Amp in most cases).