This 2009 GMC Yukon came in with the complaint that the power liftgate did not work and that the rear outside switch has already been replaced. It is the most common failure point in the system but not this time. Starting from scratch I checked the fuses and found that fuse #71 was blow. It is labeled as LGM (Lift Gate Module).
A common spot for random shorts on this series of trucks and suvs is located under the driver’s side of the dash. Just above where the driver’s left foot would rest.
The wiring harness shown that I am pointing out gets pushed down against the sharp edge of a metal bracket until it rubs through and shorts out. I installed a good fuse and checked for power on the red/black wire to confirm I had found the correct short.
Enlarging the following image shows the damaged spot on the red/black wire insulating jacket.
A little bit of electrical tape and some split loom was all it took to fix this short.