Transmission Assembly for 2017-2020 Buick Envision

A quick look at your own vehicle makes sure the right transmission shows up:

• Verify the 8th digit of the VIN is 'A' (confirming the 2.5L LCV engine).
• Verify the RPO codes on the Service Parts Identification sticker: look for 'MHG' or 'MHJ' (transmission) and 'FJM' (3.50 final drive ratio).
• Physically confirm the vehicle is All-Wheel Drive (AWD) by checking for a rear driveshaft and rear differential.
• Verify the 4-character model code on the transmission barcode tag is '7HCW' and the original part number is 24280907 (or supersessions 19434037 / 24290329).

What the install really takes — plan and budget with confidence:

Special tools this job needs:

• Engine support fixture
• Subframe/cradle jack
• Heavy-duty transmission jack
• GM-compatible J2534 pass-through programming tool (e.g., GM MDI / Tech 2 / GDS2)

Budget for these consumables at install:

• GM DEXRON-VI Full Synthetic Automatic Transmission Fluid (approx. 9 to 10 quarts to ensure sufficient volume for fill and adjustments)
• Torque converter / front pump fluid seal
• Axle output seals
• Professional-grade transmission cooler and line flush solvent
• Transmission filter kit (Note: Internal pump filter is non-serviceable without splitting the case, but external pan gasket/seals should be replaced if applicable)

What your vehicle’s computers will need after the swap:

What’s involved: VIN-specific programming (TEHCM flashing) and Service Fast Learn (adaptive relearn)

The internal TEHCM must be flashed with the vehicle's exact VIN and latest GM calibration files using GM's Service Programming System (SPS2). The vehicle may start without programming but will remain in a neutral/fail-safe state. A Service Fast Learn must also be performed with a professional scan tool to calibrate clutch fill volumes and prevent harsh shifting.

Pro tips for a smooth first start-up — hand them to whoever does the install:

• Torque Converter Seating: The torque converter must be fully seated onto the input shaft and pump splines (typically rotating and pushing until it drops 3 distinct times) before bolting the transmission to the engine. Failure to do so will crack the oil pump gear on installation.
• Temperature-Sensitive Fluid Level Check: This unit has no dipstick. Fluid level must be checked via the side check plug while the engine is idling and fluid temperature is strictly between 86°F and 122°F (30°C to 50°C). Checking outside this range causes severe underfilling or overfilling.
• Cooler Line Flush: You must thoroughly flush the transmission cooler and lines to clear out metal shavings and debris from the previous failed transmission. Skipping this will contaminate the replacement unit and void the warranty.
• Dowel Pins: Ensure alignment dowel pins between the engine block and transmission bellhousing are present and in good condition to prevent flexplate and pump damage.

Easy to get right once you know them:

• Reusing the old TEHCM to avoid programming: This transfers trapped metal shavings and debris from the failed unit directly into the replacement transmission, destroying the solenoids.
• Checking fluid level with the engine off: This causes several quarts of fluid to pour out, leaving the transmission severely underfilled.
• Failing to flush the cooler lines before installation.
• Ordering the wrong drivetrain variant (FWD instead of AWD) or ordering a unit from a different GM model (Equinox/Terrain) assuming interchangeability.

Not issues with the units on this page — the manufacturer documented these for every transmission of this family, wherever you buy one. Handy for your installer: