Coming home last night, raining, Power Brakes just went away, no warning, just gone. Brake warning light came on and stayed on.

What is top culprit?

Booster
Booster check valve
Vacuum Pump

I did go through vacuum lines and did not see in obvious cracks/holes. Also looked at nipples on vacuum block, nothing.

 

mine did that about a month ago,and it was the vacuum pump that went bad

 

does your A/C controls work if it's a vacuum pump that went out then only the top defrost vent should blow

 

As others have said, vacuum pump. Not hard repair, I've replaced mine 3 times. O'reillys and their lifetime guarantee has been well worth it!
Be careful pulling the pulley, that's the hardest part.
(and getting the darn belt back on)

 

I will check tonight, thanks!

 

I took Booster off, it holds pressure so it must be vacuum pump. I have to order one.

btw- only the defrost vents work, will not select to vent or heat.

 

go get you a vacuum pump it's done