Just throwing this out there:

Maybe someone installed an aftermarket
remote start kit and that is a valet/shut off switch.

I installed a toggle switch under the dash for my remote start so when I take it to the dealer I can disable it.
(also installed an under hood switch) If anyone looked at my van and saw the toggle switch,
they would wonder what it did also.

My remote start uses the factory key fob ... you just press the lock button 3 times to start the vehicle.

Try pushing your key fob "lock button" 3 times to see if it will start.
if not, push the switch in the glove box and try again. if not, it was worth a try.

Like I said at the beginning just trying different ideas ..... good luck!

 

Since it's not factory, tracing wires is the only way to determine what system is involved and what it does.