Child safety locks are built into the rear doors of most cars to prevent rear seat passengers from opening the doors both during transit and while the vehicle is stationary; vehicles have been built with this feature since the early 1980s. They provide the vehicle driver with a simple, safe & secure method to prevent exit from the car. Although called a child lock it is equally effective for adult passengers. The lock is typically engaged via a small switch on the edge of the door that is only accessible when the door is open. Some cars implement the locking mechanism as a rotary device which must be engaged with the vehicle key, this design prevents “sticky fingered” passengers from disabling the lock as they enter the vehicle. In both designs the lock is completely inaccessible, especially to the passenger, when the door is closed. When the child lock is engaged, the interior handle is rendered useless. Usually the inside handle just moves freely without unlatching the door. In this state the passenger cannot open the door from the inside and is effectively locked in, the passenger can only be released by someone lifting the outside handle. The child proof locks can be made considerably more secure if the they are engaged on both rear doors and the power windows are also locked, as this prevents the passengers from exiting on the other side or rolling down the window to reach the outside handle.
As well as the above mentioned mechanism, on many cars there are also window locks. These window locks prevent the windows in the back two doors of the car from opening all of the way. The windows only open to about three quarters. These were put into place from fear of a child ‘falling’ out of the window.
How to Fix a Child Safety Door Lock on a Car?
Child safety locks can sometimes jam on a car door. In order to fix it, try using a grease or oil like WD-40. If the lock is jammed or bent, it may need to be replaced by taking off the door frame and unhooking the lock.