I rigged one for a fuel pump power switch on my Suburban. Teed a pressure switch into the outlet for the gauge tube. No pressure grounds it. I wired it to a relay to give power when it is not grounded.

Switched relay power to 85, 86 to pressure switch. Switched power to 30, power out from 87a.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.