My guess is the master cylinder.......the return spring is broke or it's just hanging-up internally. Take a look for binding in the pedal pivot too.

 

18 in hg vacuum or more more is spec for the vauum pump. If you have a low pedal then vacuum is NOT your problem. Your rear brakes could be out of adjustment, ABS valve is bad, Master cylinder is bad, or you have a leak. Most common cause is rear brakes out of adjustment. For a test use a pair of vise grips a adjust them so they just clamp the rear brake hose off then hit your brakes. If its still soft then get two more sets of vise grips and clamp the front hose too. If its still soft then you either have a Master cylinder or ABS valve issue.

 

is there a way to just test the ABS actuator? since the brakes are fine and the master cylinder is withen 1 year old.

 

You still have air in the system .. maybe bench bleed the master cyl first

 

You need a new master cylinder ....

 

If the vacuum system is bad, you get no power assist, and have to push the hydraulic fluid with only your strength. Good hydraulics and bad vacuum will feel VERY hard and pedal will move very little. Do a double-leg-press on the pedal to get stopped (eventually), but you won't bottom out the pedal.

Really soft pedal suggests good vacuum (pump, lines, booster) but squishy hydraulics.

Sounds like your problem isn't vacuum.

 

Have you adjusted the rear brakes up correctly? Take my advice by clamping brake lines and report back. It is testing and will keep you from spending money that won't fix your problem. Trust me I have been down this road about 100 times....2 times this week.

 

Is that inches of mercury?