It took me so long to type, there are two more responses, WOW! Anyway, now I see that you have it wired wrong at the dimmer. or wired wrong to bulbs. Read my other post and see what's up. Look at the wiring diagram for your truck to see how switch is wired to the bulbs. Check the dimmer to see if it's feeding one contact, then the other contact per my post. No dual filaments. Just two on/four on.
See Geoge's post below.
