Blinking overdrive light on shifter?

While driving to Texas last winter, my overdrive light began blinking. I couldn't turn it off, although I am not sure it was off, as it didn't feel like it. I've had this van for 28 years and know it well. Anyway, I ended up pulling over, shutting the car off, then back on, and it stopped blinking.

The OD has begun blinking 2-3 times tops since then and same action worked. I am preparing to drive from WA to Texas in a few days, as my mom has had a stroke and it's important for me to go asap. This issue has me concerned since it happened again yesterday, and while it stopped after I just hit the od button rapidly 5-6 times, I felt a bit of hard shift from a stop to full acceleration.

The van is old, but very well maintained. The only major repair was a new transmission last year. It's a E40d, work done by an excellent transmission shop. Zero issues since completed. No codes come up when I check. After reading about this issue, I realized I've not taken it as serious as maybe I should've. I thought it was a short or other electrical issue and wasn't really serious. I've read it could be quite serious, and I'm worried I'll hurt my very expensive new transmission, or mess up torque converter, etc. I live on SSI disability and traveling with very limited funds. What should I watch for? What would be some signs it's more than the wires going up the steering column? Is there anything I should do, watch for, not do etc that could affect this issue? I've tried d/c the neg battery terminal, but no idea if it worked until I begin my 2,400-mile drive in two days. Any advice would be greatly appreciated. Thank you. Teressa