My electric door locks function properly, byut when I lock them with the electronic key fob, the rear hatch door (I don't have "barn door" rear access), does not lock. I have been told it is mostlikely the "activator". I am very adept with tools, but before tacking this, I'd like to know if there are any special "tricks", pitfalls, etc. Where is it and how do I access it the easiest way? Can I just buy the activator from GMC and replace it myself, or is it wiser to just burn a day and drive it to the GMC service center.

Thanks for your help.