Idle boost valve has no power, I'm stuck!

Hi folks, car was running fine but now won't idle at all, just wants to cut out.

I have no power to the idle boost valve and can't figure out where the power should come from?

Haynes says relay position 16, but in my car that's the header tank alarm.  1990 cabby,

This is my relay box, please help, I'm missing all this sun!!

its relay 57, check round the back for ign live on the yel/black or black wire, this is probably fed from fuse 17 or 18