Isuzu trooper diesel piping diagram

no country stated, no car stated.
no engine stated, petrol or diesel.
below is my wild and useless guess ,its petrol.
Power assist brakes work off a base of manual brakes.
my wild guess 2 is KB truck, in Africa

this next line means with booster off line
(hose plugged, and pulled)
do the base manual brakes work or not.??????????????
this is first. and a big safety issue.
is this hard to understand.?
is this your first brake job?
how the manuals work 101:
using up to 100 lbs of (man) force on the brake pedal; can get you 600 psi force at the rear of the mc, (and 4 time more at front calipers)
the pedal is 6:1 ratio, (approx)
the MC piston to the slaves (ratio) the front caliper pistons are huge (4:1), and 6x4=24:1 total . 24x100 is 2400 lbs, from you foot to pads.
the cars stops great like this.
assist only lighten the pedal load, needed.
allows 50 lb girl to drive car, or my pet chimp.
or old skinny grand ma , to church...

these facts are why the brakes still work in manual mode.
The stopping distance does not decrease with boost.
(granny excepted) one could call this granny assist.
see, in a shop full of men we can stop the car
fast and same low distance.
my guess is your post is about assist only.
not brakes dragging
not braKES WEAK.


assist is a whole other set of issues, if only assist fails....see?

Hi Rebecca,
Since the AntiLock Braking System utilizes the power (vacuum) boost to operate normally, the ABS indicator should come on if the booster fails. Yes, this means your ABS system is not able to function correctly, but neither are your standard brakes (as the extra pedal effort required to stop will tell you). however, your brakes DO WORK, so driving it to get the codes scanned shouldn't be too dangerous - just be ready to stand on the brake pedal with both feet and leave yourself plenty of room to stop by driving slowly and looking well ahead for stopped traffic. Once your booster is fixed, the ABS light should go off without any special reset or clearing of ECM memory. Good luck and happy motoring!

_______power brake booster, check vacuum to booster and the check valve for brake booster. primary symtom is high hard pedal that requires greater then normal pedal pressure to stop car. testing booster= pump brakes several times with engine off to deplete stored vacuum. turn on engine with pushing slightly on brake pedal. you should be able to feel the pedal fade away a bit, and then become firm. But not hard. if you feel nothing at the pedal when engine starts. Brake booster is not working. Good-day! make sure vacuum is going to booster with engine running. it may just be a bad vacuum line or check valve.

When your brake pedal is hard, you may need to check your brake booster and the vacuum line to the brake booster if their is sanction, if their is sanction in vacuum pipe to the brake booster you need to have your brake booster replaced.
You also need to check your vacuum pump and the piping.

You are right except you need to find out which is the culprit.

It appears that you have lost the vacuum assistance that works the power booster for the brakes. It is most likely that the vacuum hose that connects from the vacuum pump (which is usually located on the rear of the alternator) to the power booster has gone hard and split where the hose attaches to the metal piping. Check the hose for leaks or splits and re-terminate or replace as necessary. If the hose is OK then the problem could be that the vacuum pump is faulty or the rubber diapraghm inside the power booster has become faulty and developed a leak. A brake specialist would be the best option to sort out these latter problems.

booster unit has failed or not getting vacuum from engine. Check vacuum line from intake to booster unit. If vacuum is good, diaphram may have failed inside the booster.

the problem is caused by either a failed power brake booster vacuum diaphram or a loss of vacuum to the booster, most likely the booster is defective, if this is a diesel then check the enginge driven vacuum pump.

Check for fluid leaks and your brakes. If you see no leaks and your brakes are in good shape replace the brake master cylinder and bleed the system. The air you hear is because the pedal went to the floor. If the booster goes bad the pedal will get so hard you can hardly push it at all. I think you will find if this happened suddenly either you have a major leak or the master cylinder went bad.

if you are loosing pressure in the brake systemwhen depressing the pedal, it is more than likely a defective / worn master cylinder. If it was the vacuum booster your pedal would be hard to depress