Vincent 11/4/2010My low beams on my 2006 Buick LaCrosse did not work at all, and it was the HDM relay. If you look at your manual, it is located in the fuse box under the hood. This controls the low beams, provided that the low beam fuses and bulbs are not out. The Buick dealer didn't have the part, but the Chevy dealer he sent me to did. It was a $45 part plus tax. If it is the same part as the LaCrosse it is part # 15016745. It is very easy to replace, just pull the old one out and push the new one in. If you have time you can research the part on the web and get it cheaper. Rock Auto has it for around $30, and you can goggle the name and normally get a 5% coupon code. Hope this helps.