I am reporting a suspected brake system malfunction. About one block before my destination, I stopped at a traffic light and applied light pressure to the brake pedal. The vehicle slammed and jerked to a stop unexpectedly. Moments later, while turning into a parking space, I pressed the brake pedal again and the vehicle did not stop as expected. The SUV went over the cement parking post and struck a tall sign about 10 to 12 feet ahead. A large bush around the sign slowed the vehicle before it could continue into a tree. This created a serious safety risk to me and my passengers, who included one adult and two young children. Thankfully, no one was seriously injured. The suspected failed system is the brake system. The vehicle is available for inspection upon request. It was towed after the incident because I did not feel it was safe to drive. At this time, the problem has not been reproduced or confirmed by a dealer or independent repair facility because the vehicle is pending inspection. The vehicle has been reported to the manufacturer, and an insurance claim has been opened. UNKNOWN whether any electronic braking or driver-assistance system also contributed. I did not observe any warning lamps or messages before the incident. The main symptom before the crash was abnormal brake behavior at the traffic light, when light brake pressure caused the vehicle to slam and jerk to a stop unexpectedly.