Measure the voltage from TP1 to GND on the board. It’s in the manual. here’s an excerpt:
If your BED uses .11 ohm sense resistors (all v1.2 and above BEDs): The range of the pot produces maximum motor currents from around 0mA (fully clockwise) to 5A (fully counterclockwise). Now, the driver can’t supply 5A, so the full range of the pot won’t be used. A Vref of 1.76V will result in a motor current of 2A. The equasion for this relationship is Itripmax = Vref/(8 * Rs) Where Itripmax is the maximum current delivered to the motor, Vref is the voltage on TP1, and Rs is the sense resistor value.