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2022 Colorado Z71: Harsh Shifting & 'Service Transmission' Message

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Melissa G. · rep 0 · May 22, 2:31 AM · 1 replies · solved · Question

Vehicle: 2022 Chevrolet Colorado Z71

I'm having some serious transmission issues with my 2022 Chevrolet Colorado Z71 (3.6L V6). It started a few weeks ago with some harsh shifts, especially between 2nd and 3rd gear, and sometimes a noticeable delay when shifting into drive or reverse.

Now, the 'Service Transmission' message has popped up on the dash, and the shifts are even worse. It feels like it's slipping sometimes, and other times it slams into gear. I haven't noticed any leaks under the truck.

What could be going on here? Is this a common problem with the 8-speed automatic in these Colorados, and what should I expect in terms of diagnosis and repair?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 2:31 AM

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The 'Service Transmission' message combined with harsh shifting and delays on your 2022 Chevrolet Colorado Z71 indicates a significant issue within the transmission system. The 8-speed automatic transmission (8L45 or 8L90) used in these trucks can sometimes exhibit these symptoms, and prompt diagnosis is crucial to prevent further damage.

Here are the common areas of concern and diagnostic steps:

  1. Transmission Fluid Level and Condition:

    • Cause: Low or degraded transmission fluid is a primary cause of shifting problems. Old, burnt, or contaminated fluid loses its lubricating and hydraulic properties.
    • Action: Check the transmission fluid level according to your owner's manual (often requires specific temperature and engine running conditions). Note the fluid's color and smell. Burnt smell or dark color indicates severe wear.

  2. Transmission Control Module (TCM) or Solenoids:

    • Cause: The TCM (often integrated into the valve body) controls shift points and pressures. Faulty solenoids within the valve body can cause incorrect fluid routing, leading to harsh shifts, delays, or slipping.
    • Action: A professional scan tool can read specific transmission diagnostic trouble codes (DTCs) and monitor solenoid operation. Codes like P07xx (transmission range sensor, shift solenoid, pressure control solenoid) are common.

  3. Valve Body Issues:

    • Cause: The valve body is the 'brain' of the automatic transmission, directing fluid pressure to engage clutches and bands. Wear or blockages within the valve body can lead to erratic shifting.
    • Action: Often diagnosed in conjunction with solenoid issues. Replacement or repair of the valve body can be complex.

  4. Internal Mechanical Wear:

    • Cause: While less common on a relatively new vehicle, excessive wear on clutches, bands, or gears can cause slipping and harsh engagement. This is often a result of prolonged driving with low or degraded fluid.
    • Action: This typically requires transmission removal and disassembly for inspection and repair.

When to See a Shop: Given the 'Service Transmission' message and the severity of the symptoms, it is highly recommended to have your Colorado inspected by a qualified transmission specialist or a Chevrolet dealership immediately. Continuing to drive with these issues can lead to catastrophic transmission failure. They will perform a comprehensive diagnostic scan, check fluid parameters, and may need to perform internal pressure tests or even remove the transmission for a full inspection.

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