Hi,
it really sounds like an electrical issue. The transmission control module and power-train control module should store a diagnostic trouble code when it happens. You can try to have it scanned at a parts store, but chances are they won't have a scanner which can read transmission codes. However, it's worth a try.
Once you get the diagnostic trouble code or codes, then we know where to start. Without it, it becomes a guessing game.
If you can, try to get it scanned. A parts store, in most cases, will do it for free, so it won't hurt to have them try. Once you get the codes, let me know what they are and I'll be better able to help.
Please understand, I need to know if codes are present and what they are so I don't point you in the wrong direction. I am familiar with these vehicles and realize you can't even check the trans fluid without a special dip stick. I don't want you to think I'm just trying to get around helping.
Let me know. Also, feel free to let me know if you have other questions.
Take care,
Joe
Tuesday, January 7th, 2020 AT 7:27 PM