power loss need help

Okay so i have a 2001 Taurus SES. Everything was working fine until recently, when i turn the lights on at night not only are they fairly dim, the lights on the interior almost go out. What are all the things i need to check for if i am having power loss when i turn on the lights of the car?

hey man i had that same ******* problem when i hooked my subs up ur altanator might be going bad or ur battery is goign out. but take it to auto zone or any other auto part place u have out where u live and have them runa test they should be able to tell u right way

hey man i had that same ******* problem when i hooked my subs up ur altanator might be going bad or ur battery is goign out. but take it to auto zone or any other auto part place u have out where u live and have them runa test they should be able to tell u right way