I was off, this trans has closer to 140-150K on it. It is a 4L60E, forgot to put that in the title.
Took it out again tonight and it ran through all four gears just fine like nothing had happened. TCC worked exactly like @PlayingWithTBI explained it. Check Engine didn't come on again until after about 20 minutes or so and came on with the same codes. I reset the battery and everything when I got home, so I will take it out again tomorrow and see how it shifts and if the same code gets thrown. The transmission fluid was full, it actually was a little bit past the hatch marks.
While I'm glad it had 4th tonight I'm afraid the problem still remains like you're thinking @1998_K1500_Sub. I've been in my last semester of school this past fall so it hasn't been driven much besides a few weekends every month until now that I'm home for good again and have been driving it more, but even during that time, every so often, it would hang in 3rd but eventually shift to 4th.
Would a fluid change and filter change help or only complicate things at this point?
Took it out again tonight and it ran through all four gears just fine like nothing had happened. TCC worked exactly like @PlayingWithTBI explained it. Check Engine didn't come on again until after about 20 minutes or so and came on with the same codes. I reset the battery and everything when I got home, so I will take it out again tomorrow and see how it shifts and if the same code gets thrown. The transmission fluid was full, it actually was a little bit past the hatch marks.
While I'm glad it had 4th tonight I'm afraid the problem still remains like you're thinking @1998_K1500_Sub. I've been in my last semester of school this past fall so it hasn't been driven much besides a few weekends every month until now that I'm home for good again and have been driving it more, but even during that time, every so often, it would hang in 3rd but eventually shift to 4th.
Would a fluid change and filter change help or only complicate things at this point?