Lamp out problem fix
Folks, you don't need to spend any money on this.
My '03 2500 also had this problem. I learned thru these postings what was causing the problem. Unless one of your headlamps (hi &/or lo) are not working, the problem is in the connectors for the tail lights. The manual steps you through how to get to the bulbs and connectors in your tail light housings (be careful not to wreck the locking slides in the connectors; they're easily damaged!).
I was actually able to see which one was not making a connection (my problem became persistent enough) by going through the lamp check routine. First it was my left turn signal, then after I fixed that, the left brake light caused the problem. The constant dinging and flickering lamp out light drove me nuts.
Anyway, I found it, pulled the bulb and squeezed the connector pins a little closer together with a needle nose pliers. Problem solved... Lamp Out light went off and everything worked. No need to reset the computer either. Beats the heck out of spending a hundred bucks in my book.
Hope this helps you guys.