what could be problem for the tailgate not to lock/unlock, an my wiper not work? on 2002 GMC Envoy

the lock tryes to lock makes noise but it don't move,and my wipers don't do any thing. i have change black control box on it and that is not it. could it be the wiper switch?

Asked by for the 2002 GMC Envoy
Lock actuator needs to be replaced. FRONT wiper motor gives some trouble as well.