Long time lurker, first time poster, dragging up an old thread.
I have fitted a vacuum pump to my car and used a GM (Holden in Australia) switch from a 2011 onwards Cruze along with the GM pump, control relay and one way valve.
The switch has two ports, one from the engine and one from the vacuum pump and it goes directly onto the brake booster.
Ignition 12V -> Vacuum switch red
Vacuum switch brown -> to control relay brown
Fused 12V -> control relay red
Body ground -> control relay black
Hope this helps...
