I have the wiring diagram, videos and instructions for the 4-Pole Hardwire Kit with Circuit Tester # 18252, attached to this help page.
White Wire = Ground
Green Wire = Right Turn/Brake
Brown Wire = Running Lights
Yellow Wire = Left Turn/Brake view full answer...
For your 2006 Buick LaCrosse we have the Draw Tite hitch part # 36374 which is a confirmed fit and will work well for you. It has a 3,500 lb trailer towing capacity but you'll also need to check the owners manual of your vehicle for it's towing capacity and be sure not to exceed the lower of the two figures.
For trailer wiring you'd then want the # C56340 which is also a confirmed fit. For a ball mount you'd want the # 36061 and then for hitch balls # 19258 for a 2 inch ball and part #... view full answer...