Well I finally got a chance to take a look at this issue closer. I removed the surround and found the connector that runs up to the CHMSL (brake light). I used my MM and everything leading up to the light tested fine, 13 VDC with the brake pedal depressed. I removed the body panel that the light is mounted to so I could take it apart to find out what was wrong. After removing the housing from the panel (body) I quickly realized that this unit was not serviceable. It's an ultrasonically welded assembly; lens to housing. I figured since I was going to have to replace it anyway, I'll take it apart and learn a little something. I put it in the freezer to make the joint brittle so it would be easier to take apart. After 30 minutes in the freezer the pieces came apart pretty easy with the help of a flat screwdriver. Two long circuit boards with LED's, resistors, and a diode is what you will find inside. I proceeded to test all the components with my dc power supply set to 6vdc. All the LED's were fine, but the diode had to be removed to test. Once I removed the diode and tested it, I realized that was the failure point. The diode (rectifier) was bad (1N4003). And after replacing it....waala, everything works! With the help of some 5min epoxy and silicone to seal up the seam it's back on the truck and looks good (patting myself on back).
I would have taken pictures, but I realized that after the fact. Not to mention it didn't really seem like a common issue.
