Transmission Assembly for 2015 Buick & Chevrolet • Encore, Trax

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

• Confirm AWD drivetrain by verifying the presence of a center driveshaft and rear differential.
• Check the silver Service Parts Identification sticker (glove box or spare tire well) for RPO code MHB.
• Verify the engine is the 1.4L turbocharged engine (8th digit of VIN is typically B).

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

Special tools this job needs:

• Engine support fixture
• Transmission jack
• Subframe alignment pins/tools
• GM-compatible J2534 pass-thru programming tool or GM-specific scan tool (Tech 2 / MDI with GDS2)

Budget for these consumables at install:

• GM Dexron VI Synthetic ATF (8.5 to 9.0 quarts for dry fill/overhaul)
• Internal transmission filter (if splitting case/servicing during swap)
• Torque converter hub seal (front pump seal)
• Left and right axle shaft seals
• Power Transfer Unit (PTU) input shaft seal and O-ring
• Professional transmission cooler-line flush solvent

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

What’s involved: VIN-specific programming and TCM adaptive values relearn (Fast Learn)

The integrated TEHCM is VIN-locked to the donor vehicle. It must be programmed with the vehicle's exact VIN using GM's Service Programming System (SPS2) via a J2534 pass-thru device, followed by a mandatory 'Fast Learn' adaptive relearn procedure. Alternatively, the original functioning TEHCM can be physically swapped into the replacement unit, which bypasses VIN programming but still requires the adaptive fast learn.

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

• Torque Converter Seating: Must be fully seated into the pump gears (feeling/hearing 3 distinct clicks/drops). If not fully recessed, bolting the transmission to the engine will instantly crack the internal oil pump gear.
• PTU Alignment: Clean, inspect, and lubricate the intermediate shaft splines with high-pressure grease before mating the PTU to prevent spline wear or seal leaks.
• Fluid Level Check Procedure: No dipstick. Must check with vehicle level, engine running in Park, fluid temp between 185F and 203F, by removing the 11mm check plug on the driver's side of the case.
• The Tubes 9 and 10 Trap: If swapping the original TEHCM, ensure the two small rubber fluid passage tubes do not fall out or misalign, or the vehicle will have no forward movement.
• Cooler Line Flush: A professional flush is mandatory to prevent debris from the failed unit from immediately contaminating and destroying the replacement unit's sensitive solenoids.

Easy to get right once you know them:

• Ordering a FWD transmission (RPO MH8) for an AWD vehicle (RPO MHB).
• Skipping the mandatory cooler-line flush, leading to immediate debris contamination.
• Failing to perform the TEHCM VIN programming or the adaptive fast learn, leaving the vehicle in limp mode.
• Checking the fluid level with the engine off, which causes severe underfilling and immediate clutch destruction.
• Improperly seating the torque converter and forcing the bellhousing bolts, which breaks the front pump.

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: