At the back of the bus is a switch or button that must be pushed for 3 seconds or so after ignition is turned off. This is to force the driver to go all the way to the back of the bus before leaving the bus.
Doing so, there is a better chance they will notice a child sleeping away.
If not pushed, an alarm and horns come on.
Maybe if not pushed in time it also opens shuts off air to the brakes?
Don't know what all it does, but then I did not stay at a holiday inn express last night either.