my 2003 ram has the same issue with the lamp out indicator. i have recently discovered that both of my lower brake lights are not working. I have replaced the bulbs and the brake switch under the dash but still no lights???? Still trying to figure it out.

 

Welcome to the site. I moved your post to create a new and separate thread.

Get a volt meter out and check for voltage at the light sockets and then check all of your fuses. If all else fails then download the service manual from the link below and in signature and use it and the electrical schematics to troubleshoot.

 

Could be the rear circuit boards? I have read about them plenty of times over the years.
Rock Auto has them.
Good Luck.

 

I was having the same problem with my 2002 1500 about a year ago on the right side. I changed all the lights and the whole 9 yards. Finally, I completely took it apart and come to find out it was the circuit board was bad. Apparently that is a common problem with the 02s and 03s. I would go through Advance Auto Parts because they told me if that didn't cure the problem you could bring it back and get your money back

 

sounds like a circuit board to me!