Oil Gauge trouble

The 89 XJ I just bought has the small oil gauge on the right. The needle is pegged all the way to the right. Any Ideas why it would do this? What should I check for?
Also, what is the little box between the sunvisors? It has some kind of red lens on it. It it a compass, temp gauge? It currently does nothing.

Scott
87 MJ
89 XJ

Go buy another oil pressure sending unit make sure you tell them you have gauges and not lights (right next to the oil filter they cost like $10) and put that on and see if the gauge changes if it does your sending unit was bad if not buy a cheap oil gauge for like $7 make sure its the electrical one. And hook it up to see if the gauge is broke. If neither of those are the problems You have an engine problem and I don't know where to begin with that one.
As for the little box it is for the automatic door lock system I have it too but nothing inside of it.
DIG IT!