Hyundai Repair: 99 accent transmission problem, shifting into overdrive, overdrive switch

Question
I have a 99 accent that has automatic transmission with electronic overdrive switch on the shifter. The shifter knob has broken and is hanging off of the shifter but it appeared that all the electronics were still working properly. just recently my car quit shifting into overdrive while driving down the highway. It runs and shifts perfectly fine in all the other gears including reverse. I am thinking that maybe the overdrive shift sensor for the button on the shifter knob may have gone bad and is causing it to not shift into overdrive. Is this viable or could there be something more to it, and is it safe to drive the car on the highway, i don't go over the posted speed limit and don't do much interstate travelling.

Answer
There's nothing unsafe about driving your car without using overdrive.  The largest consequence is that you'll use more fuel when driving at highway speeds.

I'd guess that one or more of the wires to the overdrive switch has broken because the knob is dangling.