I have a 1999 buick century limited edition and YES (" i have checked all my fuses AND relays")
about a year ago my gas gauge stop reading it constantly reads full then a few months after that ALL of my windows went out and YES (" i bought a brand new switch") that was not the issue and now 7 months later my low beams stop working !! YES (" these were tested and work excellent ") and yes once again i checked all my fuses and relay .....ive also heard from alot of freinds and checker autoparts and autozone they think its the ECU and i just want to be sure because i am going to buy one soon so if you know my problem i would really appeciate it .