This sounds like a really elementary question but when you bleed the brakes should you have the engine running?

The reason I ask that I replaced the brake fluid in my car and now when I brake and the ABS cuts in hear a noise that sounds like a vacuum pump from behind the drivers dash.

No you don't run the engine. However use a little tube or hose and protect your tires from the fluid. You may want to pull them off. The fluid will eat the rubber.

OK thanks, I actually did the fluid swop about 600 miles ago and I did use a tube to move the fluid away from the car so as not to get it on the paint or anything else. I had the car on 4 jack stands when i did it.

I guess I will have to do more investigation for the source of my noise, but I am sure its a vacuum pump sound