When I shut down the car, the gps plugged into the power outlet does not shut down, even with the truck totally off. I assume this will drain the battery. Is there anyway to make the power source shut off when I shut the truck down? I really don't want to have to unplug the gps every time I shut the engine off.

Thanks

It's my understanding that if something operates while the car isn't running, it's going off the battery and the alternator. If it shuts down as soon as the car is turned off, then it's on the alternator and not the battery at all.

I don't think there would be any way to switch it without physically changing the wiring in the car. Can your GPS shut off automatically if you don't change location for a certain amount of time? That might be the only way to go.

This is just my understanding of it, I'm not really too much of a car person.

That socket may not be "switched"
In other words, when you turn the key off, power remains on that socket.

This may be desirable for some use : say for example you have a powered food/bev cooler or want to keep your phone charging.

If that's the only outlet, you'll need to have another wired into a power feed that is switched and protected by a fuse or circuit breaker..