Years ago I purchased an SSBC electric vacuum pump which was supposed to be able to operate independently from engine vacuum to operate the power brakes. Unfortunately the pump could never keep up with stop and go driving, rock crawling when on the brakes a lot etc, so I ditched the pump. I finally decided to give the pump another shot, but this time as an emergency backup pump. The idea is to run the brakes off of engine vacuum until the engine stalls, such as when making a steep hill climb, climbing a waterfall, etc, with a manual transmission. When caught in those situations in the past, I had one pump of vacuum boost that had to last until someone could get a strap on the front of the rig to pull me out. In one instance I nearly rolled the truck because I could not keep enough pressure in the brake system to keep the truck from slowly creeping backward, while twisting the steering wheel the wrong way no matter how hard I gripped.... Power steering was dead too. Here is the vacuum routing: 2 standard check valves and a T fitting One valve between the manifold and T One between the vac pump and T 3rd leg on the T to the vac booster which should also have a check valve Have power from your brake switch go to a relay and ground the relay through a low oil pressure switch When the engine dies and you have no oil pressure the pump will run. In addition to this I have added vacuum reservoir canister which will also add to the safety of the system. I am still waiting on the check valves so I haven't tested it out yet. I'm hoping to have everything together by this weekend.