'03 2500 hd fog light question

It is illegal to have fog lights on with brights but with some minor custom wiring you can do it.

sorry , i got on my soapbox. I assume you mean adding a relay and a switch. Do you know how I could still use the factory switch? I've already installed some piaa lights and wired them to the factory lights and switch and would like to keep it as clean as possible.

It cannot be done using the factory switch and wiring .The switch is a momentary switch going to an input into the bcm..The programming cannot be modified to allow what you want...unless you know somebody or have tons of $$ to have it custom programmed...where you would do that I don't even know Bobo