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?

by in Hardwick, VT on August 31, 2012
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1 answer
ANSWER by , August 31, 2012
Lock actuator needs to be replaced. FRONT wiper motor gives some trouble as well.