Victor turning on and off under load, with non-IFI microcontroller

[pludodog]

I'm trying to control a Victor (two 884's and an 883, all have the same problem) using the Arduino microcontroller. It outputs PWM signals that work fine for servos, and should work fine for the speed controller. When I vary the output with the motor disconnected the victor goes from red to orange to green as expected. When I connect the motor and give the speed controller a speed the speed controller flashes orange rapidly, and the motor makes a clicking noise, as if it were turning on and off quickly, but doesn't move.

Without the victor the motor works fine, the battery works fine, and the controller works fine. I haven't hooked it up to an IFI controller yet -- our only C controllers are in Atlanta and I don't want to remember PBASIC. I might build a timer circuit in the morning just to see, but it seems like the Victor is getting PWM signal fine.

Any idea what could be causing this?