Sometimes when its dusk and not dark enough to turn on the auto headlights or if its raining, ill turn on my marker lamps/parking lights (plus the truck looks cool with just the roof lights on):h ). Now sometimes when my parking lights are on (headlight knob one click up from "AUTO") my daytime running lights will be on. Other times, they are off when my parking lights are on...is there any reason they are sometimes off and sometimes on when I turn on my parking lights???

---Ben

your DRL's should only be on when you have the truck in gear.
Is it possible that sometimes you are looking at the truck when its parked and sometimes looking in a reflection when you are driving?

The parking brake effect this as well.