Prep the vehicle. Verify grounds, battery health, and use a maintainer. Confirm all transmission connectors are fully seated and there are no pin fit issues.
Connect the tool. Plug in a GM MDI2 or equivalent J2534 device (or HP Tuners where supported) to the OBD-II port.
Get the right file. On GM’s service site, enter the VIN and download the exact TECHM/TCM calibration for that vehicle.
Flash the TECHM/TCM. Follow the tool prompts to override the base file. Do not interrupt power or network during the flash.
Warm up fully. Start and reach operating temp. Check for leaks, verify cooler flow, and confirm line pressure (if your tool supports it).
Perform the relearn drive cycle.
Light-throttle takeoffs (5–15% throttle) through 1–2–3–4 at city speeds.
Part-throttle accelerations (15–30%) and steady cruise to allow adaptives to update.
Gentle decals to let coast downshifts learn.
Repeat a few cycles; avoid wide-open throttle on the first drive.
Verify & clear codes. Read DTCs, verify smooth engagement in all ranges, and confirm TCC apply/release is normal.
Final QC. Recheck fluid hot, in park, on level ground (follow the OEM procedure). Document programming and relearn in your work order.