Just wanted to thank the originator and others for this thread. I've had PSM and ABS lights coming on, at first intermittently, then constant. Mechanic read computer codes and said the sensor was bad in the hydraulic pump for the ABS and PSM - and since the sensor is integral to the pump it cost $2700. That's when I started searching the forums. I hadn't noticed my brake lights were malfunctioning, so we checked that and sure enough, they came on only as you depressed the brake and went off when fully depressed. Replaced the switch and problem resolved! Here's link to complete technical article -
Pelican Technical Article: Boxster Brake Pedal Switch Replacement / Clutch Pedal Switch Replacement - 986 / 987
As a side note, I actually went to the dealer to get the part since I pass it every day on my way to work. The parts guy isn't real bright and even though I gave him the part number he gave me the wrong part. It ended up being the clutch/switch the technical article mentions. So I just decided to keep it and replace both switches. Ends up the very next morning the car wouldn't start. Put in the clutch switch and the car started right up. The existing switch was loose, so just tightening the screw may have worked, but just replaced anyway since I had the part. For once a mistake turned out to be a good one!