Is the light constantly on or is it blinking?

IF it's solid you probably have to reset it like I did mine. Go to the fuse box under the hood. There's a 40amp fuse that says back up. Pull it and leave if out for 20 seconds then put it back and you should be set. You'll just have to reset your radio and clock.

If it's blinking you'll have to pull the code. You can go to autozone and they'll get the code for free.

Good Luck