Wiring up the Vacuum Pump

One of my goals for this kit was to utilize as much of the existing infrastructure of the car as possible in terms of fuses, relays and wires. To properly wire up the Gast vacuum pump, I wanted a fuse for safety and ideally a relay to protect the pressure switch from arcing too much.

Fortunately, the Civic had the features readily available for this in the form of the radiator fan circuit. The under-hood fuse box had a fuse and relay for this. The whole circuit was powered when the driver turns on the key, so the pump won't run with the car is parked.


This is the radiator fan connector. The black wire is ground and the black/red-stripe wire comes from the relay that powers it. I was able to cut off this connector and strip away the plastic protective sheath to use these wires.


Here is the black/red power wire connected to the positive side of the vacuum pump.


The radiator fan is triggered by a temperature switch connected to the green wire in the engine wiring harness. I was smart enough to leave many of the leftover harness wires intact and bundled up. The bright yellow wire on the left connects to one side of the vacuum pump switch.


I tied the negative side of the vacuum pump and the other side of the vacuum switch to ground via this existing 6mm bolt. The bolt is bottom center in the picture above with grey and blue wires attached to it with a 1/4" hole ring terminal.

This worked out quite well. When I turn the ignition key to the "on" position, the pump starts right up as the vacuum switch activates the relay. Both the pump and switch are fuse protected by existing fuses in the car.