Brake Transmission Safety Interlock (BTSI) is a system that requires the service brake to be depressed before the transmission can be shifted out of “park.” Before the introduction of BTSI, it was possible to shift vehicles with automatic transmissions "out of park." Unfortunately, this safety risk could occur even if the vehicle's engine was off or in accessory mode, the driver's foot was not on the brake, and the key was in the ignition. This often led to vehicle rollaway, particularly with unsupervised children playing in vehicles.
BTSI was gradually added to new cars until it was finally required in all vehicles by Model Year 2010. As a result, this type of vehicle rollaway, while possible, is increasingly uncommon. However, vehicle rollaway can still be a problem in vehicles equipped with a keyless ignition or push-button start feature when the vehicle has been turned off and not shifted into park. This is why it is essential to always engage your emergency brake every time you park, regardless of the presence (or lack of) BTSI technology.
- Always ensure the vehicle is securely in the Park position before shutting the vehicle off and exiting.
- Supervise children carefully when in and around vehicles.
- Keep vehicle locked when unattended.
- Never leave keys in the car.
- Verify whether your vehicle has BTSI by reading the owner's manual.
What You Need to Know, Now.
- Vehicle rollaway can happen in an instant. Always supervise children and never leave them alone in or around a vehicle for any reason.
- When the vehicle is set in motion, a driver may try to jump into the rolling vehicle in an attempt to stop it, only to be injured or run over. Children can also be hurt inside the vehicle, especially if they are unbelted and the vehicle is in motion. Sometimes, the vehicle may end up running over someone else or into other vehicles. Safety equipment such as air bags are not operational when the vehicle is in the Off position.
- All vehicles with automatic transmission and a Park position, manufactured for sale after September 1, 2010, must have BTSI.
- A small but growing number of new vehicles have an automatic Shift-to-Park function which is a safety feature intended to prevent vehicles from accidentally being turned off without Park being engaged. Should the vehicle be turned off before being placed into Park, the vehicle will automatically shift the transmission to the Park position.