It's just a reminder message letting you know that the deadlock function is enabled..
When you lock your doors with the remote, the deadlocks automatically engage so the doors cannot be opened from inside or out, without the proper key. The intention is to remind you that you should ensure that nobody is left in the car when you lock the doors, as there will be no way for them to get out of the deadlocked car, without breaking a window or something.
For the record, if you lock the doors with the remote while inside the car, inserting your key in the ignition slot will automatically disengage the deadlocks.
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