Weird gage readings in my car were due to weak connection there the wiring harness plugs into the instrument cluster. It's just copper tabs on the connector plug resting on bare spots in the printed circuit. A little crud/corrosion messes up the gages. I used contact cleaner from Radio Shack and gentle touch with scotchbrite pad to clean both parts and it works fine.
Try this and see if it works. Push in on the lower right corner of the instrument panel. The plug that connects to the recepticle in the panel MAY just not making good contact. If that doesn't work, take the panel out and clean the contacts of both the connector and recepticle.