The power door lock actuators may become slow to operate or stop working completely and require replacement.Google+
Car Problem Reports
GMC Suburban 1500 Power Door Lock Actuators May Fail
GMC Suburban 1500 Problem
Average Mileage: 163,047 mi (125,000 mi - 208,000 mi)
Visitor, 1999 GMC Suburban 1500, 150,000 mi
power door lock failure
Visitor, 1999 GMC Suburban 1500, 125,000 mi
door locks failed . driver door only one still working
right door and rear door locks at times do not open when the buttons are pushed.
Visitor, 1997 GMC Suburban 1500, 173,000 mi
all four doors, operates manually okay
Visitor, 1999 GMC Suburban 1500, 156,000 mi
Passenger power door lock does not lock or unlock. Will work manually.
My auto locks don't work. I can't even lock my doors.