It is most likely due to the Security Gateway Module, "SGM." I have a 2019 Ram 3500 and had a fault code in the Passenger Door Module. I could not clear it from the OBDII port. I had to isolate the SGM, then I was able to clear it. I can't say for sure where the SGM is located on the 1500's, but I had to tear my dashboard apart to get to mine because it's behind the instrument cluster on the HD's. Search for videos specific to your model on how to do that and it should work for you. By the way, you're going to need an adapter cable called the Chrysler 12+8. You'll find two wire harnesses connected to the SGM. One is a 12 pin, and the second one is an 8 pin. Ultimately you remove those from the SGM and plug those into the adapter cable. On the other end of the adapter cable is an OBDII connector that you'll use, instead of the regular OBDII port.

You should go to autoauth.com to register your scantool so you can use it on the
newer Chryslers