Lost 3rd (D) gear, Ideas???

[soutthpaw]

See if the collective knowledge here can help.
97 AWD
I was driving the can up 395 near Reno NV after crossing the 9600ft Sonora pass and as I was accelerating onto the freeway on flat ground it just revved the engine and would not go into D. However I let off the gas and then applied the throttle lightly and it went into OD (4th) no problem Got home and there was no burned trans oil, no leaks, correct level fluids, I had serviced the trans fluid and filter several thousand miles ago.
I made it back over the pass using 1,2 and then OD 160 miles or so, because my tools are at my place in CA. drives totally fine in all those gears 165K miles.

Does this sound like a solenoid issue or time to just get a rebuilt trans and swap out. can get one delivered to my door for $900 with 5 year unlimited mile warranty. swapping it out is not a big deal for me. plus I have a transmission jack already. But don't want to do that if its not necessary.

not very familiar with the 4L60E but I know its Electronic vs Hydraulic shifting. Absolutely no trans issues until this happened.
thanks

[Mmusicman]

If it's not a broken part.. then it may just be a stuck valve.
I always suggest running some "Trans-Tune" though it first before you replace it.
Available at Walmart and most autoparts stores. Nothing to lose for trying.

Fixed stuck valves on two of my transmissions.. worked almost immediately.
It is recommended to run temporarily for a few days, then change fluid and filter.

Good luck

[soutthpaw]

Also no DTC s are showing. Might try that trans tune as a last resort. Hopefully a transmission expert will add their 2 cents here. It's a second vehicle so no rush to fix it.