Dont have a clue, I thought it was only fitted to turbos and the like, but there you go.
Hence why i had first used pin 31 for normal TC,
But if your car has ESP then pin 25 must be used.
I didnt know how to tell what one was fitted,
for what its worth mine already had a wire in pin 31 (maybe thats a give away)
but the how-to says to splice into it so i did, didnt work for me.
Oliver