The "display interface" would just ground out each of the display LEDs on the dash. It would also turn off the AUTO lamp whenever the knob were turned away from the auto setting.
I've been stupid busy at work, and with the snow melting, I have a ton of household chores to do as well. This at the top of my personal priority list, but it lags behind the job (and the wife's) demands.
Oh, to be single and unemployed again...