6.6L Duramax L5P Transmission (TCM) Tuning Kit | 2017-2026 GMC/Chevy

6.6 Duramax L5P Transmission (TCM) Tuning Bundle

Overview

This L5P TCM tuning bundle gives your 2017–2026 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: 2017–2026
• 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 ->)

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):

• OBD 2 Flash Tuning Interface — Purchase separately or get it with the All-In-One DPF/DEF/EGR Delete Kit

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 (2020–2026)

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

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 (2020–2026) 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 2020–2026 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.