O/D light blinking and transmission issue?

Any codes? Let's use this guide to see what comes up, also I have seen the transmission range sensor cause issues like this as well.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Here is how to replace it in case you need it. Check out the images (below). Please let us know what you find. We are interested to see what it is.

Okay, so I just finally got to replacing that part. I guess the only thing left would be transfer case or wiring. Unless a tire speed sensor could be a problem? On the plus side. It doesn't start blinking until I hit about 40 now.

The best best is to scan it to see what codes come up, did you check out the guide above?

Just used a scanner from O'Reilly's and no codes came up. So, I basically need to find a way to a shop. Even though they didn't find any codes after replacing transmission from last time it was in shop. The only thing I can do now is to replace whatever parts that may be transmission related. But it's not like they have a list for that publicly.

The scanner the autoparts use is a level 1 scanner, you need a level 2 scanner or what they call a CAN scanner. you can get a CAN scanner (Controller Area Network) from Amazon, here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

How does the transmission seem to work? I have seen the overdrive drum sensor go out and cause this problem here is the location in the images below. Please check it out and let us know.

Transmission was replaced as I initially thought that was the problem. But I did notice something else. It seems to shift through 4 gears before it gets to 30. And sometimes it shifts hard through all gears and sometimes not. Also, if I turn overdrive off it will be high RPMs at 20 MPH. And I also noticed that if it hits a bump hard enough, the transmission will not engage and you have to shift through 4wd, 4wd low and then back again to get it to reengage. At this point I am starting to suspect transfer case itself.

I don't think the transfer case will affect the shift points, but it can affect the transmission engagement. Unfortunately, the only way you see if the transfer case is the problem is to remove it and disassemble it. Also, I don't think it will cause the OD light to blink; did you ever scan it for codes?