Does anybody know exactly what this error code means?

81 Remote radio switch input circuit high
Set Condition: Remote radio control MUX circuit is open (above 5.0 volts)

It's the only code my truck has and I don't know what it is. it also never changes the key cycle part. It always comes up as 81 00 every time.
What I do know is that my radio volume doesn't work 100%. If I turn the volume up or down it'll jump back and forth between volume levels randomly. For instance I'm turning the volume up it'll go like "10, 11, 13, 11, 12, 11, 12, 13, 12, 13, 12" that kind of thing.

 

Apparently the remote switch is behaving improperly. (steering wheel radio control?)

 

I don't even have steering wheel radio control. Only cruise control on my wheel. I'd like to find a wheel with the controls and add it in later on, but for now it isn't an option I have.

 

Is there anyway to diagnose this without a DRB3? I don't really know where to even begin looking for this problem.

I also wonder if it could be because my radio volume is faulty, but won't be able to swap radios for a while.