Traditional cruise control keeps the car at a set speed, requiring you to tap the brakes if traffic slows down. Adaptive cruise control (ACC) automates this. It uses radar sensors behind the grille or cameras behind the windshield to scan the road ahead. If the car in front slows down, the computer backs off the throttle and applies the brakes to match their speed. When the lane clears, the vehicle accelerates back to your set speed.
The radar sensors must be clean to operate. Dirt, ice, or heavy snow on the grille will block the radar signal, turning the system off. ACC also relies on camera alignment. If you get your windshield replaced or install a lift kit on your truck, the camera must be recalibrated so it scans the road correctly.