You can easily check that the motor side of your throttle wiring is working correctly by doing a simple test with the harness disconnected.
A small piece of wire
(reshaped paper clips work well for this) inserted between pins no 4 and 6 on the motor socket should make the motor run at full speed:
Make sure the wheel is raised off the ground and that the power is switched
ON before you insert the wire.
Just push the clip in enough to make contact with the outer end of both connectors. If the clip/wire diameter is too large and you press it in too far it can open out the contacts inside the connector too much so they will no longer grip the pins of the corresponding plug.
Be very careful to only put it into the correct two holes or you could end up damaging the controller or wiring harness.
If your motor runs continually during the test, you will probably need to double check the throttle connections and try and measure the voltage on the throttle signal wire as the throttle is operated. You may need to solder some temporary wires to make it easier to connect the voltmeter.
Alan