I have a dc motor mounted on a RC Car. I tried it with a 9V battery(without any controller). I just wired + and -. But it is working only one way.
Can you rotate it with your fingers both ways? Does one direction feel "rougher" than the other? Was this the motor that came with the car? What happens when you use something other than a 9V battery (which doesn't really have the current capacity needed, especially if there is some friction in the way)? What happens when you apply power in the "opposite direction" and give the shaft a spin with your fingers - does it run then?