Brake Fault Lights, Idle Drops and Brake Pedal Pulsates When Stepping Hard on Brake

[rad4runner]

Hi folks,
I searched for similar post but could not find one so I'm starting this thread.

Symptoms appear when I step *hard* on the brake:
1) Actual stopping is harder (takes longer to slow down),
2) Brake fault lights up,
3) When finally at full stop the pedal pulsates; as in alternately softens and settles (like when starting normally), then hardens up.
4) Idle also drops by about 200 RPM's

When I only step lightly, braking is normal and I do not get above symptoms Could it be a vacuum leak? Or could it be defective vacuum pump which is piggybacked on the alternator? Or could it be the vacuum booster?

Coincidentally, I also have a charging issue where sometimes the charging voltage is only 12.6VDC, not the usual 13.5 to 15.1 VDC.

Video shows symptoms....

 

[nissanh]

1) Actual stopping is harder (takes longer to slow down),: RESURFACE THE FRONT DISKS AND INSTALL OEM BRAKE PADS
2) Brake fault lights up: LOW BRAKE FLUID LEVEL
3) When finally at full stop the pedal pulsates; as in alternately softens and settles (like when starting normally), then hardens up. RESURFACE THE FRONT DISKS AND REAR DRUMS. ALSO REMOVE AND REPLACE BRAKE FLUID WITH NEW FLUID
4) Idle also drops by about 200 RPM's: WHEN DOES THIS HAPPEN?

I TOO OWN A LN 106 BOUGHT BRAND NEW IN SRI LANKA AND STILL WITH US.