The vehicle was under full self-driving mode and approaching a shopping center. There was a crossroad with signs on the corner. The vehicle was supposed to turn left but kept slowly approaching the signs on the corner. I was ready to step on the brake to stop the full self-driving mode while expecting the vehicle to turn left or step on the brake. Instead, the vehicle accelerated toward the signs, so I had to steer the wheel to the left and apply the brake immediately. The vehicle jumped a bit as it ran over the corner of the crossroad and stopped after about 10 feet. I was fortunate because I took action immediately, avoiding hitting other people or property. However, human reactions seem not to be quick enough to prevent some accidents as in this case. During this incident, the right corner of the front bumper of the vehicle hit the signs, and the top right corner of the vehicle (right above the front window) was also slightly damaged.