2018 Acadia 9-Speed Transmission Hesitation and Hard Shifts

ClearTheCode guidance (Gmc · Buying & ownership)

Summary: For 2018 Acadia 9-Speed Transmission Hesitation and Hard Shifts, work through these steps on your 2016+ vehicle:

1. Confirm the symptom — note when it happens (cold start, highway, after fuel fill, etc.).
2. Scan codes — save all pending/stored DTCs; don't clear until you've recorded them.
3. Check TSBs & recalls — look up your VIN for open campaigns and known fixes.
4. Inspect the obvious — related fuses, connectors, fluid level, and recent repairs.
5. Test the common fix — follow model-specific service procedures; one change at a time.
6. Escalate if needed — burning smell, no brakes, overheating, or stalling in traffic → shop visit.

Owner reported: My 2018 GMC Acadia Denali, with the 3.6L V6 and 9-speed automatic, has been acting strange lately. I've noticed a significant hesitation when accelerating from a stop, almost like it's searching for the right gear. Sometimes, it also has a really hard shift, especially between 2nd and 3rd gear.

It's got about 65,000 miles on it. I'm worried this could be a major transmission problem. Has anyone e…

This is educational guidance, not a substitute for hands-on diagnosis.