DETROIT — The U.S. government’s road safety agency is investigating Tesla’s “Full Self-Driving” system after getting reports of crashes in low-visibility conditions, including one that killed a pedestrian. The National Highway Traffic Safety Administration said in documents that it opened the probe on Thursday after the company reported four crashes when Teslas encountered sun glare, fog and airborne dust. In addition to the pedestrian’s death, another crash involved an injury, the agency said. Investigators will look into the ability of “Full Self-Driving” to “detect and respond appropriately to reduced roadway visibility conditions, and if so, the contributing circumstances for these crashes.” The investigation covers roughly 2.4 million Teslas from the 2016 through 2024 model years. A message was left Friday seeking comment from Tesla, which has repeatedly said the system cannot drive itself and human drivers must be ready to intervene at all times. Last week Tesla held an event at a Hollywood studio to unveil a fully autonomous robotaxi without a steering wheel or pedals.