Hope I'm in the correct forum. My wife has a 2004 SLK 320. The two main brake lights have gone out, at the same time, but the trunk brake light still works. She no longer has the owner's manual, and I can't seem to find one on-line to even find where the fuses are located, or if that's even the problem.

Can someone help me with troubleshooting why 2 of 3 brake lights won't work? I've checked the bulbs and they seem to be ok.

Thank you.