10/01/2026
On very rare occasions do we have a scenario like this where truck and its systems such as brakes, wiring, and/or computer are killing transmissions.
This “car lot” 6L80 transmission had the most damage we have seen out of ALL the 6L80s that we have done!
After rebuild, (in this case, we built up a core due to the excessive damage) the transmission operated fairly decent but had a few shift flares.
We decided to replace the TEHCM due to how much heat the old one had seen. It still had slips and flares, but this time set a P0777 code.
We decided to pull the unit, install the updated valve body with new TEHCM on this unit. Still sets a P0777 code, still feels like the brakes are dragging and we feel like the previous tech who got into this before us may messed up the case connector because it came to our shop broken with communication codes…
We are working with the client to unwind this mess of a truck and come up with a mutually beneficial solution. I think if hindsight was 20/20, we certainly would have forgone taking this truck in and I’m sure the car lot would have forgone repairs if they knew the extend of “vehicle side” issues that are contributing to the demise of its transmission.
You win some. You lose some. But the least painful path for me sometimes is just losing money and losing some time, but doing so in the quickest, least painful way possible. I don’t like handing cars back not being repaired, but this one may end up that way to avoid the client from having to spend thousands more fixing the rest of the issues this truck has.
