Can I power only one motor with Arducopter?

I put together a prototype Arducopter controller with APM 2.6. It’s been programmed for quads. Please see pic below.
Can I test only one motor, or does the controller need to see all four motors connected?
Thanks in advance.
ArduCopter APM 2.6 proto setup-2 by Dan Jacob, on Flickr

Yes you can connect just one motor to an ESC. The PWM value is just a signal which the ESC interprets as what throttle level to output. So without motors connected to the other ESC’s only the connected ESC will recognize a motor and cause it to spin. Odd way of doing things though, if you want to test a motor/ESC just connect it to your throttle channel on the Rx and raise the throttle.

Thanks, GD.
I’ve checked the motor separate from the controller - no problem.
But I’m getting a message from MP/Motor Test saying "Command was denied by the autopilot"
My controller is powered by an ESC and the JP1 jumper is installed, could that have something to do with it?
Or maybe because I skipped all the calibrations and went direct to Motor Test?