There is no switch for the marker lights.
They come on with the lights automatically.
88963884 Off Road Lamps Switch
(This is the one with the "UP" arrow on it.)
$23.49US
I can't find the ones for the Grill Lights
(The one with the down arrow in it)
http://hummer.autowebaccessories.com/store/advanced_sea...from=0&pto=0&x=0&y=0