I have a 2001 ram 1500, The brakes have very little pressure and don't work until they're all the way on the floor, and whenever it starts doing that the ABS and the brake light turn on. I've bled the brakes multiple times, the first time they worked good for about a week and the second time it lasted probably 10 minutes till it went back to that I don't see any brake fluid leaking from anywhere and the reservoir levels don't look bad I've flushed all of the brake fluid could it be a bad sensor or component in the brake system any help is good.

 

2 or 4 wheel abs? Might be a bad master cylinder. Do you see fluid, or wetness, below the master, on the vacuum booster?

The brake line going to the rear is pretty famous for rusting out and breaking as well.... and it doesn't always drop fluid on the ground. I would think you WOULD notice you were losing fluid though.

 

Master cylinder has an internal leak? Do a visual inspection on the brake lines first like HeyYou said. And/Or take the brakelines off from the master cylinder and cap them off on the master cylinder side. See what kind of feel you get, does it still go to the floor? Could be the vacuum booster with a hole in it from wear and tear. This part usually never fails though.

 

When did this start? Have a look in the frame rail on the drivers side nest to the gas tank. That's where the line bursts. You may have a small hole and it leaks out slowly. Also the master cylinder has two reservoirs one for the front and one for the back. If it has a leak the level for one or the other will go down.