• For Off-Road Use Only
    GMC L5p truck with transmission tuning file icon and Tuning Credits Icon on a white background
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6.6L Duramax L5P Transmission (TCM) Tuning Kit | 2017-2025 GMC/Chevy

Sku: L5P-TCM-KIT

This product fits:

2017-2023 L5P GM Duramax
Chevrolet Silverado / GMC Sierra 2500/3500 6.6L
$538.99
-0%
Shipping calculated at checkout.

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Within the device vehicle info section, look for the value with the text containing "14C204":
HC3A-14C204-ABH

Once you receive the device, please contact us with your serial number, VIN, and ECU strategy so we can create the custom tunes and send it to you for tuning your vehicle.

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T304 Stainless Steel

The Purest Stainless Steel used in Exhaust System Manufacturing

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High Rust Resistance

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Lasts Up To 20+ years

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Looks Better

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T409 Stainless Steel

The Standard Stainless Steel used in Exhaust System Manufacturing

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Low Rust Resistance

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Lasts Up To 5-8 Years

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Looks Dull

Attention

A 2022 Cummins Tune Package was added to your cart. This tune is a beta tune that may cause the following:

  • Low power
  • Poor fuel mileage
  • Engine codes that may appear
  • Poor shifting characteristics

For a tested and proven tune, please view our Ram Cummins 6.7L All-in-One DPF/DEF/EGR Delete Kit w/ECM Swap (2022-2024)

Attention

You have added a product to your cart that requires the Service. This required additional service is NOT included in the price shown on TunerDepot.com. This means that you will be required to pay for the Service in addition to the product you have just added to the cart.

6.6 Duramax L5P Transmission (TCM) Tuning Bundle

Overview

This L5P TCM tuning bundle gives your 2017–2025 L5P GM Duramax the advanced transmission calibration it needs to match a modified powertrain. Simply license your existing TCM and flash the included tune file to rewrite shift schedules, shift points, torque converter lock-up settings, and transmission line pressure — a complete TCM upgrade without needing new hardware.

Compatibility

  • Years: 2017–2025
  • Makes: Chevrolet Silverado, GMC Sierra
  • Models: 2500, 3500
  • Engine: 6.6L Duramax L5P Diesel only
  • Tuner Requirement: Only compatible with MPVI3 or MPVI4 tuner (Tuner not included, Can be Purchased here ->)
Year Range Make / Model TCM Transmission
2017–2019 Silverado 2500/3500
Sierra 2500/3500		 T87A 6-Speed & 10-Speed
2020–2025 Silverado 2500/3500
Sierra 2500/3500		 T93 10-Speed

What You Get

When you purchase this bundle, you receive:

  1. GM Duramax L5P TCM Tune File — Advanced year-matched calibration file for your existing T87A or T93 TCM
  2. 4x OBD2 Tuning Credits — Required to flash the tune file via your OBD2 interface
  3. Vehicle License — Standard licensing for your truck

You Will Need (Not Included):

What Changed in 2026

T87A (2017–2019)

As of early 2026, GM T87A TCMs no longer require a hardware upgrade. Your existing T87A can now be licensed and tuned directly — no new module needed.

T93 (2020–2025)

As of March 17th, 2026, users no longer need to upgrade the GM T93 TCM with a send-in service or this upgrade kit. Simply license and tune the controller as normal.

Technical Specifications

Specification Detail
TCM — 2017–2019 T87A (Existing unit) — 6 & 10-Speed
TCM — 2020–2025 T93 (Existing unit) — Diesel only
OBD2 Credits 4 credits included
Interface Required OBD 2 Flash Tuning Interface (sold separately)
Intended Use Off-road use only
Return Policy Final sale — non-refundable

Key Features & Build Details

  • No Hardware Upgrade Needed — Works with your existing T87A or T93 TCM. Simply license and flash the tune file.
  • Revamped Shift Schedules — The tune file rebuilds factory shift scheduling to better suit real-world diesel load demands.
  • Modified Shift Points — Upshift and downshift thresholds are adjusted beyond factory settings.
  • Finely-Tuned Shifts — Shift quality and timing are calibrated for consistent, predictable feel across operating conditions.
  • Optimized Torque Converter Lock-Up — Lock-up parameters are revised to improve efficiency and reduce slip under load.
  • Adjusted Transmission Line Pressure — Line pressure is recalibrated to reinforce clutch pack clamping under elevated torque conditions.

Installation Notes

An OBD 2 Flash Tuning Interface is required to flash the included tune file — not included in this bundle. Purchase it separately or with the All-In-One DPF/DEF/EGR Delete Kit.

Your existing T87A or T93 TCM will be automatically detected when you connect via OBD2. No hardware replacement needed.

Frequently Asked Questions

Q: Do I need to buy a new TCM?
A: No. This bundle works with your existing T87A (2017–2019) or T93 (2020–2025) TCM. You only need the tune file and credits to flash your current unit.

Q: What is the difference between T87A and T93?
A: The T87A is used in 2017–2019 L5P trucks (6-speed and 10-speed transmissions). The T93 is the successor for 2020–2025 L5P diesel applications. Both can now be tuned directly without hardware upgrades.

Q: I have a T93 — do I need to purchase an upgrade?
A: No. As of March 17, 2026, you can upgrade your T93 TCM directly via OBD2 for FREE. Simply license and tune as normal with this bundle.

Q: Does this bundle fit gas engine trucks?
A: No. This bundle is for L5P diesel applications only.

Q: Is the MPVI OBD Flash Tuning Interface included?
A: No. The OBD 2 Flash Tuning Interface must be purchased separately, or is included with the All-In-One DPF/DEF/EGR Delete Kit.

Q: I already own the OBD2 interface — how do I use the included credits?
A: Provide your interface serial number at checkout and the 4 credits will be registered to your device.

Q: Is this product refundable?
A: No. This is a final sale, non-refundable product. Confirm your year selection and verify you have the required OBD2 interface before ordering.

Q: What if I need a physical replacement TCM?
A: If your T87A or T93 is damaged or defective, contact us separately. This bundle is for tuning existing, functional TCMs only.

Important Product Information

Off-Road Use Only: The products sold on this website are intended for off-road use only, and may not be legal for use on public highways where pollution control laws apply.

Check Local Laws: Before purchasing and installing any of these parts, please check your local and state laws to confirm whether the modifications are legal in your area.

Professional Installation Recommended: These kits and parts are strongly recommended to be installed by professional mechanics only. Improper installation may lead to performance issues or damage to your vehicle. Unless specified differently on the product page, our parts do not include installation instructions. They are intended for individuals with a proficient understanding of mechanical systems and procedures. Like many aftermarket parts compatible with a variety of vehicles, minor adjustments or modifications may be necessary during the installation process. We cannot accept returns or offer refunds on the basis of an inability to complete the installation due to the absence of instructions.

Warranty: The use of these parts will void the warranty of your vehicle. Please confirm with your vehicle manufacturer before purchase and installation.

No Liability: Tuner Depot is not responsible for any damage or issues that may arise from the use of these parts.

Product Images: Product images are for illustrative purposes only and may differ from the actual product due to manufacturer design changes or improvements.

No Performance Guarantees: While these parts are designed to enhance the performance of your vehicle, no guarantees are made regarding the specific performance gains that will be achieved.

Shipping Policy at Tuner Depot

At Tuner Depot, we understand the importance of timely delivery for your performance parts. We're committed to ensuring a seamless shipping experience, striving to dispatch your orders with utmost efficiency and speed.

Our Shipping Policy: Our aim is to dispatch all orders within two business days, providing you with a quick and efficient processing time. However, unforeseen circumstances beyond our control may occasionally impact shipping times.
Factors Affecting Shipping:
  • Weather Conditions: Adverse weather conditions such as rain, snow, or sleet may affect delivery timelines. We will make every effort to minimize any delays.
  • Holiday Periods: Please note that our shipping center will be closed during holidays. We will resume shipping promptly on the next business day. Allow for potential delays during peak seasons, but rest assured, we will keep you informed every step of the way.
  • Staff Availability: Unforeseen circumstances can occasionally affect our staffing levels, possibly leading to minor delays. We are committed to swiftly resolving any issues to maintain our high standards of service.
We genuinely appreciate your understanding and patience during any unexpected obstacles. Be assured that we will utilize every resource available to deliver your performance parts promptly.