Totally a guess but I could imagine that the ABS and PSM are linked. As for brake sensors, you don't mean the pad wear sensors do you? If you track and/or otherwise maintain your car regularly (which I'm sure you do!) you can just eliminate those and twist the wires together. Sort of like the clutch switch.
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James now has: 2008 987S 6 speed
Crashed: 2010 987.2 pdk in speed yellow!
Sold to a cool racer chick: 2004 986 S
YouTube channel: the PORSCHE as seen by NewArt
www.youtube.com/channel/UCohdrH2xHTklM1thxk0KKOQ?