I have a ’00 F150 ext. cab with 4.2L V6. Recently the gauges will intermittently go wacky, jump from max to min and back while driving. Then when I park it the battery drains. Now, it is just the voltage gauge that intermittently goes to H & the battery light will come on. When I slow to a stop the needle goes down and the light goes out. When I start again it goes back to H and the light comes on. Also, I can hear a very faint clicking sound coming from the left side of the instrument cluster (opposite the voltage gauge.) I have been disconnecting the battery when I park so I do not have to jump it anymore, annoying but it is working. I have tried many things to no avail. Does anyone have any ideas out there?
Facts: This has been a great truck for me and everything is stock. No major breakdowns except the PCV valve that was very difficult to get to. A month ago the alternator and battery failed and were replaced, I just had them both retested to be sure. I just flipped 100k miles a couple of months ago.

 

well first off u wana get yourself a voltage meter like 10 bucks for cheap one, check your voltage at your battery when the in dash meter is reading high, if infact your voltage is more then 14.5, your voltage regulator is probably gone, it's built into your alt so you will need to replce it, about your drain it probably is possible thet your alt s sorting out insidde so it could lso cause the drain... try that.

 

Thank you for your response. I changes out the alternator and have had not electrical problems. When I tested the battery when the error occurred, it read 18V. I actually had to show the guy at the parts store to replace the part that has a lifetime warranty. Pisser. Oh well it got done, thanks.