Chevrolet Repair: Trailblazer speedometer problem, powertrain control module, speedometer needle

Question
I have a 2005 Chevy Trailblazer 4X4 with the L6 engine. I'm having trouble with the speedometer. It seems to stick slightly at around 65 or 70mph and after a certain amount of time will gradually just keep moving until it reads 120mph. Sometimes it goes all the way around, just very slowly. At a stop it will come halfway back and just sit there. I discovered that if I pull the fuse to the instrument panel and wait a few seconds then reinsert the fuse, it resets the speedometer to zero and it works fine for a few more days, then does it all over again, but its becoming much more frequent. Any ideas?? I do alot of my own mechanical work, but I don't know alot about instrument panels or speedometers. Any help is appreciated, thank you.

Answer

ground erratic operation of the speedometer. speedometer needle shakes above 96 km/h (60 mph).

Cause

This condition may be caused by a loose or poor connection at Powertrain Control Module/Engine Control Module (PCM/ECM) ground G108.
Check this ground pic attached