GMC Repair: 1999 Suburban - Weak Door Locks, penetrating lubricant, acuators

Question
My 99 Suburban has electric door locks that seem to be getting weaker.  The passenger, and two rear doors try to lock and unlock (can hear the relay) but only slightly move and don't engage.  The rear door doesn't do anything at all - doesn't sound like it is getting any power. What do you think?
Thanks, Alan

Answer
Hi,Alan
 What it sounds like is the door lock acuators are begining to bind,try to lube the acuators by spraying a penetrating lubricant into the door lock latches,this may free them up,if not the acuators need to be replaced,GM has issued updated acuators,also you can check the ground G110,this is located under the drivers side frame rail just ahead of the drivers ft door,you can remove the bolt and clean the ground and reinstall,this may also help.

ED