Possibly a faulty indicator light, which would probably be a rare occurrence.
I would hook up your trailer, get on the highway, note what your RPMs are at what ever your typical towing speed is, say 60mph, for a few miles. Now turn off the OD and your RPMs should be higher probably closer to 3,000 and should not downshift and drop to a typical OD RPMs of around 2,000. That's best I can tell you.
If you need more input you should start your own thread with the topic of your problem. That way it will show up in the JK forum not under the this members title of TPMS commander issues but say like your own title of "overdrive light not working". That way you'll get responses to your issue. Good luck.