Brake lights not working, but turn signals are???

On my '06 2500, when I hit the brake pedal, the brake lights do not come on. When I hit the turn signal indicator, the turn signals work fine. The 3rd brake light does work when I hit the brakes.
This doesnt sound like an issue with bad bulbs, does it? I sure hope its not some sort of difficult wiring issue....Im going to look into it in a little while, I just thought I'd see if anyone has dealt with that type of issue here first.

Thanks!!

Anyone?
I never found time to look into it yesterday

did you probe around the brake light sockets with a test light? They are a different light bulb than the turn signal bulbs, arent they? How's the trailer harness?

First, check the bulbs. I'm amazed how many vehicles I see with one of both burned out.
Next, since your truck should have separate bulbs for the brake lights but the 3rd works (proving out the fuse and switch), check for power at the bulbs. If there is no power at the bulbs, check under the back. The most common fault is where someone hacked into the rear harness for the tow lights. Then where the harness follows along the frame, forward to the cab. Additions and damage should point to the areas to inspect closer. Last, get the wiring diagram and find where the wiring goes through the bulkhead. Check for power there. If you still have no power, it's going to be under the dash.

You've heard of Canbus? If I remember right, and I'm not sure I do, even the lights run through the instrument cluster due to canbus. I've heard of some VERY weird seemingly unrelated problems solved by replacing the instrument cluster on some of these newer trucks. FWIW, YMMV, no warranty express or implied in this post.

Robert