4L80E GM Transmission TCC Failure
We recently had a 2006 one ton cube van with a slipping/shuddering transmission (4L80E). The transmission code indicated a torque convertor problem. The first step was to remove the transmission oil pan and check the filter. It was advised by one of the transmission shops to tear open the filter and see what's inside. We found lots of grayish/black material and metal filings. It was confirmed that the torque convertor clutch had failed.
The factory torque convertor comes with an internal clutch that operates the lockup of the convertor. Unfortunately the torque capacity of the clutch is limited. Once the clutch starts to go bad the weight of the vehicle along with the required torque demand will cause the clutch to unlock the torque convertor completely and cause a downshift into third gear. This causes the shuddering the driver was complaining about.
The transmission had to be removed and most likely rebuilt according to the 2 rebuild shops I called up. To be safe the trans would need disassembly and overhaul to get all of the contamination out of the system. They estimated $3,000 dollars would be the cost to repair. Just out of curiosity I phoned around to the 2 GM dealerships for a price. To my surprise the replacement trans was $700 dollars less than a rebuild and would come with a 3 year warranty. Sweet!
This G van was going to be running around in our fleet for a while so the GM reman was the best option. A three year warranty is excellent coverage for any rebuilt component. One of the dealerships had one on the shelf so everything worked out perfectly. According to the mechanic working on this job the electronics checked out OK at the very start. The clutch lockup was initiated but didn't happen because of the mechanical failure of the TCC.
All is well now and with a fresh load of synthetic transmission oil and a good road test this vehicle is ready to go back to work. The radiator we had tested at the radiator shop checked out good for cooler flow and cleanliness. They gave it a good flush with the tools needed which saved us some time. Thank you for reading this post. I have more coming as it happens in our fleet operation.