“My car is trying to kill me!” our customer stated to a service manager. She went on to explain that when she engaged her adaptive cruise control that the vehicle would advance dangerously close to the vehicle in front of it then brake hard. She explained how scary the vehicle behavior was and again stated, “My car is trying to kill me!” The service manager promised to get to the bottom of the issue and report back.
He turned it over to a talented certified technician with a great deal of Advanced Driver Assistance System (ADAS) expertise. The technician road tested the vehicle to confirm the condition and performed an electronic scan of its systems. There were no diagnostic trouble codes (DTCs), indicating all the systems relevant to the adaptive cruise control were functioning. Knowing a probable cause, the technician inspected the front radar system and performed a calibration. The factory procedure called for two major steps. First, the radar is to be properly leveled and aligned, a mechanical operation similar to aligning a headlamp. The radar system was mounted on a light weight bracket which was distorted, no doubt due to some impact. The distorted bracket was replaced. After it was properly aligned, the technician performed an electronic calibration, which was done according to factory repair procedures. This includes the positioning of specific factory-designed targets at a specific distance and position from the vehicle. A scan tool was used to calibrate the radar, essentially having it “look at” the target and calibrate itself relative to the target location. (Think of it as being kind of like centering the cross hairs in a rifle scope.) A post-repair scan, for safety and quality confirmation, again indicated no trouble codes. A road test revealed that the adaptive cruise control was back to functioning as designed, without the scary characteristic of driving up on vehicles then braking hard. It was concluded that the radar system being out of calibration was essentially not looking in the correct direction and therefore not seeing the vehicle in front of it until it got too close. This is a true story.
The situation described above is just one example of what can happen with ADAS systems that are not performing as designed. The more we’ve worked with these systems, the more such examples come to light. For example, there was the steering angle sensor that was out of calibration which caused the vehicle to ‘think’ it was not going straight and its accident avoidance system would turn the steering wheel to the right as a passing vehicle pulled up on the left side. The system thought moving the car to the right would avoid a collision from the left. And there was the vehicle whose blind spot monitor wouldn’t indicate an advancing car in its right-side blind spot until the car was almost next to it. Turns out the blind spot sensor was out of calibration AND there was too much paint and plastic repair on the bumper cover which further distorted and diminished the systems ability to ‘see’ the vehicle in the blind spot. Again, these are just a few true examples of what can happen with malfunctioning ADAS systems.