Here's how power door locks work in your car:


Door locks keep the interior of your vehicle secure. Power operated door locks work with an actuating mechanism controlled by the car's ECU.

Here's a look at the latch and lock mechanism removed from the vehicle:

There is a lot of levers that are actuated by the exterior door handle, the interior door handle, the door thumb lock, the power door lock, and in the case of the front door, the key.

The latch grabs onto the striker on the body of the car. "Locking" the car merely disables the door handles from opening it.


Inside the power door lock actuator is a small motor that turns a gear to push and pull the lock arm rod.


Interestingly beneath the gear, there are contacts with diodes, which form a built in protection circuit so the motor isn't over worked against the gear train. You can't lock a locked door, and vice versa.

 

Thanks for another one of your usual informative, detailed videos. For those interested, I'll add a little tidbit of history to it.

Up until the late 1960s, there were no safety-regulations covering the use of door locks....the manufacturers could more or less design them as they saw fit. In many vehicles, even if the doors were locked from either the inside or the outside (and power-door-locks were usually seen only on luxury/premium-level cars at that time), if one pulled on the inside door-release, it would override the door locks and pop the doors open. This was obviously a potential hazard for kids, or even adults, riding in the rear seat, as this was also an age when seat-belts and/or harnesses had not yet become mandatory, either. A few vehicles (I think from Chrysler, but I"m not sure) had non-overriding inside handles on the rear doors, which offered some protection, but it generally was not the norm.

The Motor Vehicle Act of 1966, which was passed largely from the efforts of Ralph Nader and his organization, mandated, among many other things (including the much-needed seat belts), non-overriding inside locks, on all four doors, for all new American-spec vehicles. That meant that, once the doors were locked, you could not open them with the inside handle until you first specifically unlocked the doors themselves. This, of course, made it much safer for kids in the rear seat....and that safety-measure, of course, was also integrated into the sliding doors of minivans when they first appeared on the market some 15-20 years later.

As for the hidden child-safety switch, hidden in the rear doors where kids couldn't get to it when the doors were closed and locked, that device was not mandated on new American-spec vehicles until legislation was passed in 1985. Before this switch was installed, kids could unlock (and potentially open) the rear doors from the inside, even if they were locked from the outside, by simply pulling up on the lock-button or pushing the rocker-switch. The Child-Safety switch prevented that...once set by parents, anyone in the rear seat could not unlock the doors, period, from inside, until someone let them out. This made for a greater level of safety in general, but, of course, could be a problem if there was a vehicle-fire or other emergency and one had to get out of the rear seat very quickly.