Vr6woes Very cool project. Here are my thoughts:
Behavior of the speed controller doesn’t sound that unusual. A lot of electronics will exhibit unusual behavior when you have open circuit and input (throttle pins) are left floating.
Typically the throttle control will get 0-5V from the speed controller and supply back 0 to ~ 3.5-4V over a third pin that tells the speed controller throttle position. 0V would correspond to off and 3.5 to 4V would correspond to max throttle.
I searched Amazon for this product and found this writing diagram. Not sure if it’s exactly what you have.
To rule out issues with the speed controller, try shorting the 0V pin on the throttle connector (Speed adjustment in this diagram) to the throttle speed input (Signal input pin). This should put the motor at 0% throttle and verify that something is not messed up with the speed controller. If this works, good sign that you have the right pins/connectors and that the speed controller isn’t stuck at max throttle. When you unshort the pin, I’d expect it to go back to wide open throttle b/c that sounds like the behavior of the controller when the throttle input is left floating.
Before connecting up anything though, I’d double. check that you are working on the right pins/connectors. Best way to do this is with the supplied sheet + verify voltages using multimeter in voltage measurement mode if you have one.
If that goes well, second thing I would look at is the throttle control. Verify that you have the correct pinout (0V, +5V, Signal output). You should be able to connect the throttle to 0V and +5V, then monitor the signal voltage output using a multimeter. You’ll connect one pin of the multimeter to 0V and the other to the signal output pin on throttle.
As you twist the throttle, you should see the voltage on the multimeter going from 0V up to whatever the max voltage is. If you aren’t getting that, then either you pinout is incorrect, you have connected something incorrectly, or the throttle is broken.
Caveat with using the multimeter: make sure you are operating in voltage and not current mode. If you make the measurements described above in current mode, you’ll just blow out fuses on the multimeter and wonder why it’s not working correctly.
Hope this helps! Please update us on your progress.