My brakes paedal went to the floor and the brake light came on with I P on the top. The pedal is very soft. I filled the master cycl. and pump the brakes they cam up but a few seconds later they were soft again. What can I do to fix this problem myself?

Check for leaks in brake system. From master pump down to the ones at the wheel.

It could be that your brake fluid reservoir is empty. You might also have a crack in the line.

bad master cylinder.. normal for pedal to get hard while pumping pedal with engine off.

once should have been enough to get it fixed
indicates a master cylinder failure
go to a brake specialist shop for a proper diagnosis and quote
the master is probably original and is well past a replacement maintenance period

if master cylinder is bad. the pedal will go to floor running or not.when the pedal goes down at a standing stop it is usually the master cylinder thats bad. and losing vacuum. thats if there are no other leaks at wheel cylinders etc. if putting on a new master cylinder, do not forget to bench bleed it! heres how. put the master cylinder in the vise, fill it full of fluid then pump the plunger with a dowel or something soft as to not ruin plunger part.do not let it run dry ! when fluid comes out from master cylinder and no more air is in it. fill it up and put on car. heres what I do! remove the lines from old cylinder on car. as long as you do not lose any fluid doing this, there is no need to bleed air from brakes when done. after on car make sure master cylinder is full of fluid. start the car and pump the brakes a few times, then you should be all set.

Master cyclinders never look OK. You have to fill em full of brake fluild ( all the way to the top) and pump the breaks lots and hard. recheck the fluild and if it went down look under the truck to see where it's coming out. If you can't find it look in the floor under the break pedal where the pedal rod goes though the floor. Fluild coming out here is a bad master cyclinder, if no leak is found put in still more fluild and pump till you find wher it's runnung out. if the fliuld stays full and the pedal goes all the way down the master is bad. Masters fail alot on older Isuzu trucks.

IF your brake pedal went to the floor, then you have a brake fluid leak somewhere. Even though you filled the reservoir with brake fluid, the system now has air in it. The first thing you need to do is find the leak and repair it. Most likely a wheel cylinder or caliper piston leaking. Once the repair is done, you will need to bleed the air from the rake system. Since you don't know anything about the brake system, I would strongly suggest having a professional mechanic do the work. If it is not done right, your brakes could fail.

It sounds like master cyl. is drawing in air causing prob. also another test would bee too bleed out and get pedal back, now step on pedal and hold firmly and see if pedal creeps near floor indicating innternal leaking in master cyl. also have some one pump bakes slowly aand look for air bubbles in brake res. after bleed out indicating master cyl. is drawing air upon release of pedal.

There may be air in the lines. Bleed all your brakes starting at the farthest wheel from the resevoir, and finishing at the closest one. Try the pedal after its bled. If the pedal still feels soft or travels to the floor there may be a pinhole leak that may be spraying on the underbody of the car, or the seals in the master cylinder are gone filling the vacuum booster(if equipped). Air compresses more than oil so if bleeding works that may be the problem.

are they hard or soft to break at the pedal? or normal? if normal NO if soft/squishy YES if too hard... drain some fluid? or check master break cil.

short answer: only need to if there is something wrong.