Multiple Instrument Guage Malfunctions Simultaneously

[Danny Key]

Hi, this is Danny in Va. I have a 2006 Toyota Land Cruiser with only 69,900 miles on it. Last Friday, 3 of the instrument gauges began malfunctioning. Simultaneoulsly, the voltage guage pegged to 13+ volts, the Fuel Guage pedded as far below E as possible, (although I had just filled the tank), and the Oil Pressure Guage increased to within 1/8 inch of H. I had the alternator tested by Advance Auto and by a reputable shop. Both reported it was putting out 13.49 volts. I also found an electrical schematic of all fuses and verified that all fuses that appeared to related to guages were good via Ohm meter. Although the guages were malfunctioning and still are, the truck runs fine. The vehicle is currently in a shop being diagnosed at $100/hour and the owner says it may take them days to find the root cause. Has anyone ever had this happen to them and/or does anyone have any ideas what the problem might be? Thank you so much, Danny