GM Says This Strange Trax and Trailblazer Vibration Is Normal

No Fix Required

Two of General Motors’ most affordable vehicles, the Chevrolet Trax and Trailblazer, may exhibit vibrations when parked facing downhill. However, the Michigan automaker says the condition is ‘normal’ and has instructed dealers not to take any further action.

The condition is outlined in GM’s dealer service bulletin PIC6553B, as shared by GM Authority. The vibration stems from the engine mount snubber contacting the mount housing when the vehicles are parked facing downhill. For reference, the vehicles in question include 2024–2026 model-year Trax and 2021–2026 model-year Trailblazer units.

The Setup That Causes It

The Trax and Trailblazer are sourced from South Korea, with the former continuing to sell well despite exposure to import tariffs. Both also use a turbo three-cylinder engine, which is inherently less balanced than a typical four-cylinder and generally produces more vibration. That may make the condition more noticeable in these vehicles, as some owners have pointed out.

Still, GM argues that it is not a defect. The bulletin said the vibration can be reproduced when the vehicle is shifted into Park and the brake pedal is released. It may also become more noticeable when the air conditioning is switched on, likely because the engine is working harder to run the compressor.

The bulletin provides a 0.2-hour labor operation to verify the condition, but says no further action should be taken if the dealer can duplicate it. This condition was initially addressed in 2024, but was recently updated to include later Trax and Trailblazer model years.

Parking Habits Matter

While it is debatable whether GM should issue a revision to eliminate the vibration, it is generally good practice to avoid shifting into Park without a parking brake whenever the vehicle is resting on a slope. Doing so places the load on the parking pawl, a small component inside the transmission that locks the drivetrain to prevent the vehicle from rolling. The ideal method is to keep a foot on the brake, engage the parking brake first, and then shift into Park. Some drivers shift into Park before applying the parking brake, but either way, anything is better than letting the transmission do all the work.

For now, owners should expect to continue experiencing the vibration under those conditions. A separate case involves thudding sounds reported from the Trax’s three-cylinder engine, which GM said in a service bulletin is a normal characteristic and not an indication of a defect.