How does lockup swich work?

[Arturo]

I bought a car and the guy gave me a swich for the torq converter. How does it work? Where do you plug it?

 

[phillyturbosix]

Ground one side of the switch and send the other wire to the top pin on the far left on the ALDL connector under the dash to the left of the radio.

 

[Arturo]

Thank, but what does it do when do I turn on and off. I have no idea what it does?