2000 Boxster tail and brake lights not working
 

Please help! Both left and right brake lights and the HMSL (center brake light) do not light up when the brake pedal is pushed. Also, the tail lights are out but the headlights come on. My turn signals and backup lights work so the ground (metal frame) in the rear light assembly must be good. The fuse for the brake lights (B7) is good and the bulbs are good. I suspect a possible relay problem but my Bentley manual is missing the page that lists the relays in the footwell relay panel. That page is blank - I guess a printing error.
Please let me know if there is a brake light relay and, if so, which one it is in the footwell panel. Also any other related advise would be appreciated.Thanks!

Check the condition of both front side-marker bulbs. Replace if necessary. That solved my problem, near identical to yours. Report back your findings. Good luck.

For a 2002 and non-functioning brake lights check the brake light switch above the brake pedal lever. The brake light switch on my 2002 Boxster wore out and the brake lights stopped working.

For the amount of work you have to go through to remove the old switch and test it with a volt/ohm meter might as well just replace the old switch with a new one. The switch is not very expensive. I paid less than $15 for one some years back.

You can replace the switch yourself but it is a bit of work to get under the dash and swap out the switch. My local dealer would have a tech replace the switch/bulb if I bought the hardware at the dealer. A tech can replace the switch in about the time it takes to write this sentence.

Actually, the brake light switch, the cruise control deactivation switch at both the brake and clutch pedal, the clutch interlock switch, I replaced all of these.

+1 on what Macster said.

I had this exact problem on my 996 C2 where the brake light switch had failed. I needed the flexibility of a gymnast to wedge myself underneath the dash, and wished I had been a contortionist. The first attempt was painful, but after replacing the brake light switch, the clutch pedal switch was a quick 10 minute job afterwards.

Check the bulbs first because it is the quickest and easiest option, then replace the brake light switch. On my 996, it threw an ABS error. I'm not sure if it does the same on the Boxster, but it's a good replacement item regardless given the age of our vehicles.

Brake lights now working properly
 

Thanks to all who wrote suggestions regarding my brake light problem. Those suggestions were correct and the problem was the brake light switch. Now that I replaced it, the lights work fine. The comments that said it was an inexpensive part were correct. And the comments saying that it is incredibly awkward to remove and replace the switch were right on! My back still hurts from squeezing under the dash - and I'm a thin guy.
Here's a bit of advice that I can contribute to the forum. i noticed an intermittent/poor contact to the brake light bulb on the left side. The ground contact is made to the bulb by the steel frame of the light assembly. The frame has two formed "ears" in the frame that contact the sides of the bulb and they weren't tight enough for a reliable contact. I squeezed them together a bit with a pair of pliers and found that the bulb made a much more positive contact after that. If you have an intermittent light problem check for a similar poor contact with the ears of the steel frame.. It's a LOT easier fix than replacing the brake light switch.
thanks again to all for your advice.

Glad to hear you resolved your problem. Thanks for following up!