09 Expe transmission stays in 1st gear only

[Trifecta991]

250K miles, Transmission code = 6. 2 wheel drive. Truck stays in first gear and runs great otherwise. Fresh trans fluid change, proper level, all fuses check out (PCM / TCM). Truck has been sitting more this past year and previously shifting without any hesitation. Looking for potential diagnostics and ultimately a solution. Shifts through to park, neutral, drive, reverse with no issue.

 

[S20Workstation4]

Any codes for the transmission?
I would first try resetting the battery and PCM by jumping the cables: https://www.youtube.com/watch?v=hZAsoqmqhdM

Seems more like an electrical issue than a mechanical issue.....


Joe

 

[Trifecta991]

Thanks @S20Workstation4 I've been considering electrical too. Followed the reset video on the PCM reset and test drive showed only 1st gear again. Considering the grounding locations at this point. Other potential solutions to explore?

 

[DieselMonk]

Can you communicate with the TCM using a scan tool?