Try overwriting the SetupInputComponent in the player controller.
in your Customplayercontroller.h:
virtual void SetupInputComponent(void);
in you Customplayercontroller.cpp:
Super::SetupInputComponent();
InputComponent->BindAction("Aleft", IE_Pressed, this, &Customplayercontroller::YourFunction);
You should be able to find some examples on the web. Put any code you want in YourFunction.