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2020 Acadia 9-Speed Transmission Hesitation and Hard Shifts

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Chris P. · rep 0 · May 22, 3:38 AM · 1 replies · solved · Question

Vehicle: 2020 GMC Acadia SLT

Hi all,

I'm having some significant issues with the transmission in my 2020 GMC Acadia SLT, which has the 3.6L V6 and the 9-speed automatic. The car has about 60,000 miles on it. Lately, I've noticed a lot of hesitation, especially when accelerating from a stop or at low speeds. It feels like it's struggling to find the right gear, and sometimes it shifts really hard, almost like a jolt.

The check engine light has come on a couple of times, but then it goes off. When I scanned it, I got a generic P0700 (Transmission Control System Malfunction) code, but no specific gear codes. It's making city driving pretty unpleasant and I'm worried about long-term damage.

Is this a known issue with the 9-speed in the 2020 Acadia? What could be causing this, and what should I tell the dealership when I take it in?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:38 AM

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ClearTheCode admin answer:

Transmission hesitation and hard shifts in your 2020 GMC Acadia with the 9-speed automatic are concerning symptoms, and the P0700 code confirms the Transmission Control Module (TCM) has detected a fault.

Common Causes for 9-Speed Transmission Issues:

  1. Software Glitches/Updates: Early versions of the 9-speed transmission (9T50/9T65) often had software calibration issues that could cause erratic shifting.
  2. Valve Body Problems: The valve body controls hydraulic pressure to engage gears. Malfunctions here can lead to delayed or harsh shifts.
  3. Solenoid Issues: Shift solenoids can stick or fail, preventing proper gear engagement.
  4. Fluid Condition: While less common at 60,000 miles for severe issues, old or contaminated transmission fluid can contribute to poor shifting.
  5. Internal Wear: In some cases, internal components like clutches or bands can wear prematurely.

Diagnostics & Next Steps:

  1. Check for TSBs: Your GMC dealership can check for any Technical Service Bulletins (TSBs) or recalls related to your specific transmission and model year. There might be a software update available.
  2. Transmission Fluid Inspection: Have the fluid level and condition checked.
  3. Diagnostic Scan: A professional scan tool can access more specific transmission codes (P07xx series) that your generic OBD-II reader might not display, helping to pinpoint the exact solenoid or circuit fault.
  4. Road Test: A qualified technician should perform a road test to experience the symptoms firsthand and monitor transmission parameters.

When to See a Shop:

It's crucial to get your Acadia to a GMC dealership or a reputable transmission specialist immediately. Driving with significant transmission issues can lead to further damage, potentially requiring a costly transmission rebuild or replacement. Since the P0700 code is present, the TCM has logged a fault, and a professional diagnosis is necessary to prevent escalation of the problem.

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