Automatic Transmission Torque Converter problems of the 2018 GMC Canyon

For several months, we are now continuously experiencing a shaking and shuddering of the Canyon every time the truck shifts from 1st to 2nd gear. It is very disturbing driving down the street and the Canyon begins to shake so hard that everyone is jarred in their seats even with seat belts on. It is almost as if the Canyon is being rear ended by another vehicle as we're driving down the street. Our biggest concern is that it happens on major roads whenever we accelerate after a traffic light transitions from red to green. As we clear the intersection, the shaking occurs and as the Canyon reduces speed momentarily, we have almost been rear ended. Our Canyon is still under warranty as we have the extended powertrain warranty. Furthermore, we just learned of a gm service bulletin, 18-na-355 dated August, 2019, that has been circulating. We found a copy of the torque converter clutch sb and it applies to all GMC Canyons from 2017-2019. Needless to say, gm (corporate and dealership) want us to pay out of pocket for a very expensive diagnostics test (e. G. , hundreds of dollars) to confirm there is a problem and then determine if warranty will cover the repair(s). This is a very serious vehicle safety issue that can cause accidents if the driver is not accustomed to being tossed about in their seat while driving the Canyon. Gm needs to do a recall to fix this problem for all affected vehicles as people, especially those that are on fixed incomes, are not able to pay out of pocket for a test just to validate the toque converter clutch shudder does exist.

6 different occasions same issue. No sound when trying to start. 10 minutes later vehicle starts and cel is lit. Never auto shifts after ~30mph. Replaced torque converter and transmission body valve on 1st occurrence. Each time serviced (warranty), and at some point the problem will occur again. Total of 6 times since purchased new.