Update to my first post on this.

08 997 TT, 5800 miles, just got the car in Nov. Drove it a few times then one
day I went to start and got "depress clutch", tried a few times and it started.
Replaced the clutch micro switch, drove it the next day and when I tried to start
later, key on-"PSM" and "ABS" fail, key to start "depress clutch". Left it for the
night and came back with a new battery, Interstate 94r, started fine. Next
time I drove same issue again, sometimes get a few more fault messages but
always "PSM" and "ABS" at key on and "depress clutch" at key to start.

Took it to the dealer, no warranty, long story as the car has Champion 700 kit,
tech says sometimes it starts and sometimes it fails as above. They replaced
the PAS module, clutch cruise switch and brake switch. I had the DME tested
and re-flashed, tech disconnected and cleaned all ground points and checked
all relays. He still says he can get it to fail every 6 to 9 key key actuations.
Waits a while and recycles the key and it starts. Sometimes the PIWIS
"sees" the DME and sometimes it doesn't when it fails, still shows code 15sv,
no start voltage.

Stranger yet, tech says when he disconnected a buss bar under the drivers
side dash and manipulated it and it's wires he was able to get it to fail on
cue, not sure which wires, he is going to look into it, but when I was able
to get it to restart I had been under there moving pedals and wires??????

Waiting for PCNA to get back to him, they no longer will talk to me.
Anybody have any ideas?