Separating motor shield from Uno with switch

Hi,

I'm using this motor shield - http://playground.arduino.cc/Main/AdafruitMotorShield

with a uno rev 3. I've removed the jumper that connects the power from the motor shield to the uno in an attempt to separate the power supplies. But when I plug in the uno to my computer with the usb cable, I get power in the motor shield and if there's a sketch in the uno, the sketch starts up and triggers the motor shield.

I want to be able to upload a sketch to the uno without the motor shield continuing to process the already uploaded sketch.

How do I keep the uno from feeding power to the motor shield while I'm uploading a new sketch?

My idea, (tried it and it didn't work), was:

  1. Remove the power jumper on the motor shield.
  2. I installed a switch to turn the power on and off to the motor shield. I turned the switch off, which should've stopped everything. (it didn't)
  3. Plug in or keep the usb plugged into the uno.
  4. Upload a new sketch.
  5. Turn on the switch to give power the motor shield.
  6. And I'm on my way.

Once again, the question is: How do I keep the uno from feeding power to the motor shield while I'm uploading a new sketch?

Maybe I should be doing this with an easy driver, but I like the practicality of this motor shied because I plan on adding an additional stepper later.

Thanks.....Antonio