Buick Repair Questions? Ask a Mechanic for Answers ASAP
From what you are describing here, it sounds like the Brake Pedal Position Sensor is getting stuck or failing in the cold weather. This sensor plays a role in the cruise control system by turning it "off" when the brake pedal is depressed. So when the lights are on, the sensor is telling the cruise system to turn off. The sensor is located under the driver's side dash, at the top of the brake pedal arm (click here for any image). Inspect the electrical connector for any signs of water intrusion. If the visual inspection checks ok, replace the Brake Pedal Position Sensor (aka "Brake Light Switch"). If my answer has helped you, please help me by leaving a rating using the stars at the top of this page or accept the answer so I may be credited. If you cannot rate or do not see the rating stars, please let me know. You can ask follow-up questions after you rate.