8-Speed Automatic Transmission Assembly for 2014-2019 Cadillac CTS - Rear

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

• Verify the 8th digit of the VIN is '8' (3.6L Twin-Turbo LF3 engine).
• Verify the SPID label in the trunk lists RPO code 'MGG'.
• Confirm the vehicle is Rear-Wheel Drive (RWD).
• Visually check the transmission case tag for 'TL-80SN' or 'AA80E'.

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

Special tools this job needs:

• Heavy-duty transmission jack
• Engine support fixture/bar
• Professional-grade diagnostic scan tool (GDS2/Techline Connect)
• Fluid pump/filler adapter

Budget for these consumables at install:

• Toyota Genuine ATF WS (GM Part #88863400 or ACDelco 10-4062)
• Transmission Filter (GM Part #24270604)
• Pan Gasket (GM Part #24270007)
• Front Pump Seal / Torque Converter Seal (GM Part #9031145032)
• Professional Transmission Cooler-Line Flush

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

What’s involved: TCM Adaptive Relearn (Service Fast Learn)

sources differ: Arm 1 states no VIN programming is required if reusing the original TCM, but a Service Fast Learn is mandatory. Arm 2 states a TCM adaptive relearn is required using a GM-compatible scan tool (GDS2) to clear old adaptive values. Cautious choice: Yes, dealer-level tool is required to perform the mandatory adaptive relearn to prevent immediate clutch damage.

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

• Torque Converter Seating: Ensure the torque converter is fully seated (three distinct clicks/drops) before bolting to the engine to avoid cracking the oil pump gear.
• Precise Fluid Level Check: Must be checked with the engine running, transmission fluid temperature between 95°F and 113°F (35°C to 45°C), using the standpipe level-check plug on the bottom of the pan.
• Mandatory Cooler Line Flush: Debris from the previous failed unit must be flushed out to prevent immediate damage to the highly sensitive Aisin solenoids.

Easy to get right once you know them:

• Confusing the Aisin 8-speed with the GM-built 8-speed (8L45/8L90) and buying Mobil 1 LV ATF HP fluid instead of Toyota WS fluid.
• Using generic Dexron VI or multi-vehicle ATF which causes solenoid sticking and harsh shifting.
• Checking the fluid level with the engine off, leading to severe underfilling and immediate transmission failure.
• Skipping the mandatory TCM adaptive relearn procedure.
• Ordering a transmission from a standard 3.6L V6 or AWD model instead of the RWD Twin-Turbo LF3 model.

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: