Brake Shift Interlock Failure

Brake shift interlock failure can be blamed for a large number of accidents in which a car mysteriously rolls down an incline while the vehicle is presumably in park. Almost a century ago, something called an interlock device was invented to prevent a similar scenario from occurring. Since 1914, various forms of the interlock device have been developed such as the brake transmission interlock, brake shift interlock, and starter ignition interlock.

If the driver's seat is unoccupied, a brake transmission interlock applies the brake. It will also do this if seatbelts are not properly engaged. In a vehicle equipped with a brake shift interlock, it is impossible to change gears (e.g., park to reverse) without pressing the brake. A vehicle with a stick shift containing a start ignition interlock will not turn on unless the key is inserted and turned, and you step on the brake. The start ignition interlock on an automatic vehicle requires the motorist to shift into park or neutral in order to turn on the car or take out the key.

It is not yet standard procedure for all vehicles to come equipped with an interlock system, but at such a minimal expense, it is difficult to make a valid excuse why they shouldn't be. Unnecessary rollaway accidents causing considerable property damage and even catastrophic injury (e.g., child hit by runaway vehicle) could almost be avoided entirely; an auto accident involving a shift out of the parked position is often caused by curious children who are able to set the vehicle in motion due to the absence of a brake shift interlock. Most children are not intelligent enough to realize the brake needs to be pushed for a gear shift to take place.