Hello, I hope someone can shed some light on the problem as it is driving me nuts. The voltage gage on the instrument panel reads between 11 and 13 volts. With the a/c on and maximum blower the needle dives towards the left side. The voltage at the battery posts with the engine on idle and a/c on maximum reads 14.2 volts, same reading with the a/c off. The outside lights do not dim at any time and the truck drives good. Using the driver side controls to lower or raise the windows also makes the voltage gage on the instrument panel nose dives towards the 0 volts. On occasions the outside temperature reading and the compass on the mirror act up, start to blink and eventually go blank until the engine is turned off and started again. This is now happening every time the engine is started. I had the system checked at an auto store and both the battery and alternator passed the test. The battery is 3 1/2 years old and the truck starts with no problem. I checked and cleaned the 3 ground connections on the frame under the driver's seat with no improvement. Anyone having this problem, would appreciate your input. Tks