I bought a Toy SR5 recently as it looked near new and drove as such. I noticed one of the things I was to do was to get new tires. After a couple of weeks, I had the money and went to Big-O. Before buying tires, I asked tech, Why did the chk. air pressure light come on and stays on? He did not know and replaced tires. I asked the Toyota dealer in town the same question as the new tires, checked pressure, and so on, did not make a difference as the light is still on. What can this be?