99 Denali having some issues

hi everyone. I have a 99 Yukon Denali that i just bought and having some issues. I just noticed that my headlights are staying on all the time. No matter if its sunny out or not...auto headlight is keeping them on. Where is the sensor located at first off? Also what can i do to fix this? Also, im getting the same chirp-clunk from my rear area when i take off, is it diffently the yoke that needs greased? Any info would be nice...just bought this bad boy on tuesday the 11th. Thanks

Check your owners manual. Maybe the are on like running lights. How about a bad univerasl joint.