A vehicle shudder and a growl or humming sound may be present when driving between 28-53 mph (45-85 km/h) on some 2024 Envista and Trax models equipped with the 6T40 automatic transmission (RPO MNH). (Fig. 1) The shudder or noise may be due to an internal torque converter condition that causes slipping.
TIP: Before beginning diagnosis for the shudder or noise condition, review Bulletin #23-NA-194, which covers a similar concern and is much more likely to resolve the issue.
Fig. 1
Vibration or Booming Noise
Bulletin #23-NA-194 covers a low drumming or booming noise heard through the vehicle speakers of some 2024 Trax models when the engine RPM is between 1,500 and 2,000 RPM under a steady load. The noise, which may be present with the radio turned off, may be caused by the Active Noise Canceling (ANC) system.
To verify the condition, manually shift the transmission to a gear to allow the RPMs to remain close to 1,800 RPM.
If the vibration or noise is present, a service calibration is available to update the A11 radio (RPO IOR). Refer to A11 Radio Programming and Setup in the appropriate Service Information.
Torque Converter Replacement
If the radio software is up to date after following the service procedure in Bulletin #23-NA-194 and the shudder or noise still occurs, the torque converter should be replaced. (Fig. 2)
Fig. 2
Refer to Torque Converter Removal and Torque Converter Installation in the appropriate Service Information. Be sure to use the required special tools.
For more details, including part numbers, refer to Bulletin #24-NA-242.
– Thanks to Mark Kevnick
