The transmission pressure control solenoid may fail causing erratic shifting. Our technicians tell us that partial dis-assembly of the transmission is necessary to replace a failed pressure control solenoid.
Average mileage: 94,132 (8,684–159,000)
15 people reported this problem
The transmission downshifts while driving steady(constant speed) this occures at 60 mph and at 30mph mostly, at least these two speed ranges are the most notable. The shifting is erratic and and does not occure frequently, maybe 2 or 5 times a month. One time at 60mph it shifted from overdrive down to second and the engine rpm jumped up to approx 4000rpm. The GM dealer and 3 garages have been no help.
slowed down to make a corner, accel and wife said engine went to 4000, like in went to "n". pulled over, restarted did the same. pulled over and turned engine of, restarted ran fine. had trans tech look at, test drove several time no problem. he pulled the pan, found some metal on the magnet. serviced filter, fluid. test drove again, fine. wife drove home 40 miles ran fine