2010 Toyota 4Runner Owners Manual - Page 131

1-6. Theft deterrent system Engine immobilizer system The vehicle's keys have built-in transponder chips that prevent the engine from starting if a key has not been previously registered in the vehicle's on-board computer. Never leave the keys inside the vehicle when you leave the vehicle. Vehicles without a smart key system The indicator light flashes after the key has been removed from the engine switch to indicate that the system is operating. CTH16AS004 Vehicles with a smart key system The indicator light flashes after the "ENGINE START STOP" switch has been turned off to indicate that the system is operating. 106