Some owners of 2014-2018 Buick Enclave, LaCrosse or Regal vehicles may comment that the vehicle might have a severe launch shudder in first gear from a stop or while driving in fourth gear, or during the 2-3 upshift or 3-2 downshift. Conditions may include a flare, slide/bump, slip or harsh shift.
The condition may be caused by debris in the upper and lower valve bodies or valve scratched or scored, causing them to not move properly. Note that launch shudder may be induced/duplicated by power braking in first gear but should only be attempted for five seconds or less to not cause any distress to the 1-2-3-4 clutch assembly.
If the concern is not isolated to be an engine misfire, drivability concern or TCC shudder concern, do not replace the TEHCM. If the shudder can be induced during a power braking event in first gear, then both the lower and upper valve body assemblies should be replaced.
About the Author
Information courtesy of Mitchell 1
Information for Technical Service Bulletins comes from ProDemand, Mitchell 1's auto repair information software for domestic and import vehicles. Headquartered in San Diego, Mitchell 1 has provided quality repair information solutions to the automotive industry since 1918.
Mike Mavrigian
Motor Age Editor
Mike Mavrigian has written thousands of automotive technical magazine articles involving a variety of specialties, from engine building to wheel alignment, and has authored more than a dozen books that crisscross the automotive spectrum. Mike operates Birchwood Automotive, an Ohio shop that builds custom engines and performs vintage vehicle restorations. The shop also features a professional photo studio to document projects and to create images for articles and books.