I have the seeed studio motor shield v2 and I am using pin I1 and pin I2 to power a motor with a 9v power supply. When I run the motor with I1 HIGH and I2 LOW it runs fine as it supplies about 4.5v. But when I1 is LOW and I2 is HIGH then the power supply barely gives out 0.1v. So going clockwise works fine but counterclockwise does not run as there is barely any power being supplied. Any possible reasons for this or could it be something wrong with the board?
Hi,
Welcome to the forum.
Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Thanks.. Tom.. 
blob123789:
...with a 9v power supply...
Would that be a 9volt smoke alarm battery?
If so, they can't provide the current to run a motor.
Your motor could be more efficient in one direction than in the other.
Making it just run in one direction, but not in the other.
Leo..