How do you shut off gas cap light on 2008 grande caravan?

Assuming there is no other problem remove the cap entirely and when you put it back on listen for three clicks. If you don't have it on all the way the system doesn't pressurize properly and the light will come on. If that doesn't do it try removing the ground wire on the battery for about 30 seconds and reconnecting it. If that doesn't work go to your local auto parts store. Most of them have a code reader that can reset it for you and tell you why it came on to start with and they will do it for free hoping to sell you a part. If you go to a dealer most get a flat 75 dollars just to reset it.