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2020 Grand Cherokee Limited - Harsh 8-Speed Transmission Shifts

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Sarah K. · rep 0 · May 22, 3:23 AM · 1 replies · solved · Question

Vehicle: 2020 Jeep Grand Cherokee Limited

Hello fellow Jeep owners,

I'm experiencing some concerning transmission behavior with my 2020 Jeep Grand Cherokee Limited, equipped with the 3.6L V6 and the 8-speed automatic. It has about 40,000 miles on it. Lately, the shifts have become very harsh, especially from 1st to 2nd and 2nd to 3rd gear, both upshifting and downshifting. It feels like a noticeable lurch or clunk.

Sometimes, there's also a slight delay when shifting into drive or reverse after starting the vehicle. It's not constant, but it's happening more frequently now. I haven't noticed any warning lights on the dash yet, but the feeling is definitely not normal. Has anyone else encountered this with their 8-speed transmission in a Grand Cherokee? What was the fix?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:23 AM

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ClearTheCode admin answer:

Harsh or delayed shifts in the 8-speed automatic transmission (ZF 8HP) in your 2020 Grand Cherokee can be a cause for concern, though sometimes they can be resolved without major repairs. Here are common causes and steps:

  1. Transmission Software Update:

    • Often, manufacturers release software updates to refine shift logic and address known issues. This is a very common first step for transmission complaints. A dealership can check if your vehicle has any pending updates.

  2. Transmission Fluid Level and Condition:

    • Even though these transmissions are often considered 'sealed for life,' fluid levels can still be critical. Low or degraded transmission fluid can lead to poor shifting. Checking the fluid level on these units requires specific procedures and tools, as there's no traditional dipstick.
    • Contaminated or burnt fluid indicates a more serious internal issue.

  3. Valve Body or Solenoid Pack Issues:

    • The valve body controls the flow of transmission fluid to engage different gears, and solenoids within it regulate this. A faulty solenoid or a problem with the valve body itself can cause erratic or harsh shifts.

  4. Mechatronic Unit Problems:

    • The mechatronic unit integrates the transmission's electronic control unit (TCU) and valve body. Issues here can lead to a wide range of shifting problems.

  5. Torque Converter Issues:

    • Less common for just harsh shifts, but a failing torque converter can sometimes contribute to rough engagement or shuddering.

When to See a Shop:

Given the complexity of modern automatic transmissions, it's highly recommended to have your Grand Cherokee inspected by a qualified transmission specialist or a Jeep dealership. They can perform a diagnostic scan for any stored trouble codes (even if no light is on), check for available software updates, and properly inspect the transmission fluid level and condition. Continuing to drive with significant transmission issues can lead to more severe and costly damage.

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