Hey all,
I just picked up a 30k mile AV6 trans and installed it into my 04 TL. Install went pretty smoothly, trans seems to work great. But I have an intermittent issue where the trans will shift down into 4th, the blinking d light comes on along the check engine light and stability control light. I get P2770 and P0977. I swapped shift sonoid b from my old trans. And bench tested both. No change, I also bench tested the torque converter clutch Solonoid. No issues with that either.

When it acts up, I can shut the car off, clear the codes and drive another 50 miles perfectly fine.

Any ideas?

yup. Fresh DW1. I broke down and finally took it to a shop, they said it sounds like an electrical issue and the only thing he could do is test the harness one wire at a time. So I guess that’s my next course of action. My only concern is that an intermittent issue may not show it self when testing continuity through the harness.

also. How can I check if my PCM is up to date?