Katemonster33:
The resistance is about 7.5 ohms.
Well the motor plate says its 3.6 ohms (5.4V / 1.5A), but I think that's when used unipolar (its a 6 wire
motor?), so its 3.6+3.6 = 7.2 ohms when used bipolar.
For bipolar use it will need 18V or higher supply for a chopper driver because the IR product is 11V,
giving no voltage headroom at all for the chopper - that's why its misbehaving with the chopper driver I think,
the current feedback isn't working properly due to insufficient supply voltage.
It also explains why it hasn't completely fried the DC motor shield.
Many steppers are more like 1 to 3 ohms and don't work without choppers from reasonable supply voltages.