Greetings, all 4 caution lights came on and tachometer needle points down in between center of the 4 caution lights, (no buzzers) no blinking check engine light or any of the other lights and engine runs perfect in all phases? Unhooked battery to try a reset w Neg results. I am mechanically inclined and have all tools and doom. Bad ground? Fuse? Can access tach easily. Thank you