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2020 CT5 3.0TT Hard Shifting and P0700 Transmission Code

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Mike T. · rep 0 · May 25, 2:50 AM · 1 replies · solved · Question

Vehicle: 2020 Cadillac CT5 3.0TT Premium Luxury

My 2020 Cadillac CT5 3.0TT Premium Luxury has been acting strange lately. The 10-speed automatic transmission has started shifting really hard, especially between 2nd and 3rd gear, and sometimes from 4th to 5th. It's not smooth at all, and feels like it's clunking into gear.

Last week, the check engine light illuminated, and when I pulled the codes, I got a P0700. I know that's a generic transmission control system malfunction code, which usually means there's another, more specific code stored in the transmission control module (TCM).

Has anyone with a CT5 experienced similar transmission issues? What was the underlying problem, and how expensive was the fix? I'm worried about major transmission work.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:50 AM

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ClearTheCode admin answer:

The P0700 code on your 2020 Cadillac CT5 3.0TT indicates a general fault within the transmission control system. As you correctly noted, this code typically points to one or more specific diagnostic trouble codes (DTCs) stored within the Transmission Control Module (TCM) itself. The hard shifting you're experiencing is a direct symptom of this underlying issue.

Here are the common causes and diagnostic steps:

  1. Retrieve Specific TCM Codes: The first and most crucial step is to use an advanced scan tool capable of communicating with the TCM to pull the specific transmission-related DTCs. These codes will provide a much clearer direction for diagnosis.
  2. Low Transmission Fluid: While sealed, transmission fluid can still leak or be low from the factory. Low fluid levels can cause erratic shifting and pressure issues. Check the fluid level and condition if possible, though many modern transmissions require specific procedures.
  3. Transmission Solenoid Issues: Solenoids control the flow of transmission fluid to engage gears. Faulty or sticking solenoids can lead to harsh shifts, delayed engagement, or no engagement of certain gears.
  4. Valve Body Problems: The valve body is the hydraulic control center of the transmission. Issues within the valve body, such as worn bores or sticking valves, can cause significant shifting problems.
  5. TCM Malfunction: Less common, but the Transmission Control Module itself could be faulty, leading to incorrect shift commands.
  6. Internal Transmission Wear: In some cases, internal wear or damage to clutches or gears can cause hard shifting, though this is usually accompanied by other symptoms like slipping or grinding.

When to see a shop:

  • Immediately, as continuing to drive with significant transmission issues can lead to more severe and costly damage.
  • A qualified transmission specialist will have the necessary diagnostic tools and expertise to accurately identify the specific TCM codes and pinpoint the root cause of the hard shifting. They can perform fluid pressure tests, electrical checks of solenoids, and inspect the valve body.
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