I ran into this and figured some guys might want this info.
Basically you can run your high beams and low beams at the same time unlike factory. All you need is a regular relay, some wires and some time.

The wiring goes :
-Power in (30) - 12v from truck,
-Power out (87) - connect to yellow wire on headlamp.
-Switch (86) - connect to green wire on headlamp
-Ground (85) - to truck ground.

Here is a write up on the install :
High 4 - Writeup

 

Cool info. I wonder if there's a way to use that to keep the fogs on with the brights as well?

 

I know there is something you can buy... but im sure its just a matter of time till someone posts info on how to do it

 

As long as you have 2 seperate relays in your UHFB you can use a simple diode. On my 03 suburban, I used a 12 volt diode 2 for a buck at RadioShack. Add the diode to pin 85 on the high beam relay and pin 85 on the low beam relay. About a 15 minute job. Most time consuming part was carefully unplugging the two relays to install the diode. Been working perfectly nearly for a year:
http://www.mcttrucks.com/gallery/my03bbburb/106085.jpg

Another thing you can do is add a jumper or another diode from the lo beam side of the first diode to pin 85 on your DLR relay. This will give you a 6 hi system and give you fog lights with just your DLR's.

Other places that this has been discussed are:
http://www.gm-trucks.com/forums/inde...howtopic=26712
http://mct.truckmoxie.com/forums/top...56246&q=4%2Dhi

On keeping the fog lights on with the hi beams, this is illegal in many areas. Also, what good is it going to do. In a situation when you need the fog lights, you don't want to have your hi beams on anyway.