2019-2026 GM 8-Speed RWD Torque Converter Shudder TSB

General Motors has issued Service Bulletin PIP6127B to address customer concerns regarding a "shudder, vibration, or surge" experienced during vehicle operation in certain 2019-2026 Chevrolet and GMC models equipped with an 8-speed rear-wheel drive (RWD) transmission. This bulletin outlines a restriction on torque converter replacement, emphasizing a diagnostic and repair process to ensure the correct fix for the GM 8-speed shudder.

The primary purpose of this bulletin is to guide technicians in determining if a torque converter replacement is truly necessary, particularly by ensuring that a specific transmission fluid flush procedure is completed first. This helps prevent unnecessary part replacements and ensures a more cost-effective and accurate repair for the GM 8-speed shudder.

Symptoms

Owners of affected vehicles may report a noticeable "shudder, vibration, or surge felt during vehicle operation." This sensation typically indicates an issue within the drivetrain, often related to the torque converter or transmission.

Important Warnings for Owners and Technicians

General Motors has placed a restriction on ordering new torque converter parts without prior authorization. This is a critical step to ensure that all other diagnostic and repair procedures have been exhausted first. The bulletin explicitly states:

"Prior to considering torque converter replacement, ensure the transmission fluid flush procedure outlined in 25-NA-148 has been completed and all diagnostic paths have been reviewed. If the concern persists after all diagnostic procedures have been completed and part replacement is still required, contact PQC for part authorization. Follow the established PQC process and submission guidelines applicable to your country below. Ensure the request includes the restricted part number and the associated PI (Preliminary Information document)."

This means that simply replacing the torque converter without performing the recommended flush (25-NA-148) may not resolve the issue and could lead to unnecessary costs or repeat repairs. Owners should be aware that their dealer will likely perform the fluid flush first.

Diagnosis and Repair Process Summary

For technicians, Service Bulletin PIP6127B outlines a structured approach to diagnosing the GM 8-speed shudder:

1. Determine Payment Type: The first step is to ascertain if the torque converter request is for customer pay or warranty. For customer pay, the flush procedure (25-NA-148) is recommended as a potentially lower-cost solution. For warranty cases, the process moves to the next step.
2. Verify Flush Procedure: Technicians must confirm if bulletin 25-NA-148, which includes a full transmission fluid flush and a 200-mile (320 km) drive cycle, has already been followed. If not, this procedure must be completed before proceeding.
3. Re-evaluate Shudder: After the flush and drive cycle, the technician checks if the shudder or vibration is still present, specifically in manual 7th gear. If the issue persists, the Product Quality Center (PQC) must be contacted for part authorization. If the issue is resolved, standard Service Information (SI) diagnostics should be followed for any remaining concerns.

Dealers in North America, including Canada, are instructed to contact the Product Quality Center (PQC) via One CRM, email ([email protected]), or phone (1-866-654-7654 for Canadian dealers) for part authorization if a torque converter replacement is deemed necessary after following all steps.

Affected Components and Part Numbers

This bulletin specifically concerns the torque converter in 8-speed RWD transmissions. The following part numbers are referenced for various models and model years:

• 24050271: For Chevrolet Silverado and GMC Sierra models with L84 engines and MQE transmissions (2019-2022).
• 24051541 or 24049689: For Chevrolet Colorado, Canyon, Silverado, and GMC Sierra models with L3B engines and MQE or MQF transmissions (2023-2026).
• 24050270: For Chevrolet Silverado and GMC Sierra models with L3B engines and MQE transmissions (2019-2022).

These part numbers are subject to the restriction, requiring PQC authorization before ordering.

Warranty Information

For warranty repairs related to torque converter replacement, the labor operation code is 8644810. Technicians are instructed to use the published labor time for this operation.

Bulletin Revisions

Service Bulletin PIP6127B was initially created on July 27, 2026. It was revised on August 27, 2026, to add question 1 to the correction steps, and again on October 5, 2026, to update the part listing.

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Source: NHTSA ID: 11038463