Converting power outlet from unswitched to switched

I have a 2000 Chevy Astro Van with many outlets for electronics. They are all live even when the ignition is off. I would like to convert one of them to become active only when the ignition is on. Can you help?

There is a large gague pink wire off the ignition switch you can tap off,then just access the outlet for hook up.

Assuming you are only looking at low power devices on this circuit OK, but if it is a high power circuit (big amp?) then you will want to use that circuit to power a relay on a high power circuit.

I agree with Joseph. If you are running something that uses a lot of power, like a cooler, I recommend you unplug it before you shut the van off. Otherwise, Oldschool has given you your answer.