2003 Silverado 2500

I don't know how applicable this will be for you, but on my '04 (built in late November '03) the headlight switch has an Off position that is spring-loaded so when you turn the switch to Off it returns back to Auto. However, whatever exterior lights happen to be on at the time (either headlights, marker lights or DRL's) turn completely off when it does. The only lights that don't turn off with the switch are the dash lights. Cycle the switch back to the Off position (where it will again spring back to the Auto position) or shutting the truck down and restarting it again turns on whatever lights were on originally. I guess this switch design was in response to the people who for whatever reason wanted to be able to shut off all exterior lights completely. Trucks built for different areas, markets, or countries may not have this feature but you may be able to order this switch for your '03 (and maybe get the Body Control Module reset for this switch). I have found that most of the electrical and electronic functions of your truck can be altered in the on-board computer's settings, so you might want to investigate that first before looking for a new switch or adding something aftermarket.

Cheers - Jonathan

In the older Silverados the head lights would go off if you pressed the emergency brake even a little bit.

I have an 03 Sierra 2500 and both are applicable