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
1 answer
Lock actuator needs to be replaced. FRONT wiper motor gives some trouble as well.