I HAVE A 1999 F150 4X4 THAT HAS HAD SOFT PEDAL PROBLEMS EVER SINCE I CHANGED THE BRAKES THE FIRST TIME. TRUCK HAD NICE FIRM PEDAL AT THE TOP WHEN I BOUGHT THE TRUCK, BUT WHEN IT CAME TIME TO CHANGE THE BRAKES, THE PEDAL WENT SOFT AND HAS NEVER REGAINED THAT NICE FIRM PEDAL. I HAVE CHANGED EVERYTHING ON THE TRUCK...BRAKE PADS - ROTORS - BRAKE LINES - MASTER CYLINDER, EVERYTHING SEVERAL TIMES!! BLED THE BRAKES A HUNDRED TIMES. TOOK IT INTO 3 DIFFERENT BRAKE SHOPS AND THEY ALL SAID THAT IS JUST THE WAY THIS YEARS BRAKES ARE. BULL..I SAY. ROTORS WERE GETTING EATEN UP OVER AND OVER...HAVING CHANGED THEM 6 OR 8 TIMES BEFORE I UNPLUGED THE ABS UNIT UNDER THE HOOD. I AM CURRENTLY ON THE SAME ROTORS FOR THE PAST 3 YEARS NOW. BUTTTTTTTT.....I STILL HAVE A SOFT PEDAL THAT GOES TO THE FLOOR AND DOES NOT LOCK UP THE BRAKES WHICH SCARES ME TO DEATH!! CAN ANYONE WHO MIGHT HAVE HAD THIS PROBLEM HELP ME?????? PLEASSSSSE??

 

Don't drive the truck until you get this straightened out.
First thing to do is check the master cylinder push rod length.
If missadjusted the cylinder piston seals are not in the correct location over the ports.
It's terrible for a brake shop to tell you what they did knowing full well no brake system is supposed to work like that.
If they were to let a vehichle out of their shop and it resulted in an accident, guess who's a@@ would be in a sling, liability wise.
.
There has to be an answer to this because liquids do not compress, only air and gasses unless mechanically the pressure is being lost.
Hope it's your answer.
Good luck.

 

I GOT YOUR ANSWER AND I AGREE WITH YOU WHOLE HARDEDLY, THE SHOPS SHOULDN'T BE ABLE TO GET AWAY WITH IT. I HAVE BEEN BILKED FOR OVER $600 TRYING TO FIX THIS PROBLEM. I AM SO GUN SHY NOW THAT I AM AFRAID TO TAKE IT INTO ANOTHER SHOP.
WHAT IS REALLY WIERD IS THAT WHEN THE CARD IS SHUT OFF, I HAVE A HARD PEDAL ALL THE WAY AT THE TOP, BUT AS SOON AS I START THE ENGINE, THE PEDAL DROPS TO THE FLOOR.

 

I assume this is a full disc brake system, not rear drums. Have you checked all 8 caliper slide pins for seizing?

 

YES, IN FACT ALL FOUR CALIPERS ARE BRAND NEW AND FUNCTIONING CORRECTLY. KINDA WIERD EH??

 

I've always bled brakes rr, lr, rf and lf. I know if abs is involved and fluid was lost from that unit some require a scanner to activate the abs to bleed air from the abs module. Now recently I watched this Motorweek video and Pat Goss had changed the bleed sequence. I don't know if it has any relevance to your problem but it's worth a look. Bleeding Brakes | MotorWeek

 

I might add that in rare instances the brake booster can be defective and pull the pedal down and not let it return.
Look at he actuating rod length.
Good luck.

 

If this is a 4 wheel abs system not rabs, my manual says to bleed master cylinder first. Then RR, LR, ABS control module, RF, LF. It says a diagnostic scanner is needed to command the abs module to cycle. I wouldn't think the module needs bleeding for caliper or hose changing as long as the master cylinder resevoir wasn't allowed to drain dry, however a master cylinder or steel lines to the module being changed might, depending on how new fluid was added. Before I do any brake pedal pushing I usually add fluid and let it gravity feed the lines I changed until fluid runs freely from them before final tightening of the fittings.

 

i am having this same problem and have since day one with my 1997 f150 4x4 with abs. i bout the truck a little over a year ago. a local mechanic (who i trust and he does good work) replaced all the brakes and shoes (has rear drums) and all the rusted out lines. and still have very soft break peddle. it goes all the way to the floor before i have anything. but i can lock up my wheels. also my abs light is on could that cause anything?

 

I had a problem with my truck rotors and pads wearing out in 25000 miles, so I thought that I would change the brake calabers and brake lines alone with the pads and rotors. After I blead the brakes I had a soft pedal that went all the way to the floor. I blead the brakes 4 times still same problem. with the help of three different mecantics the soft pedal was still there. I gave up and took the truck to a brake shop. he had the problem solved in about one hour. come to find out that I had put the calabers on the wrong wheels. I know now to always work on one wheel at a time and make sure the bleeder valve is at the top of the calaber. also I have a teenager that was driving my truck could be the reason that the breaks wore out so fast hope this helps some one like me that trys to do ther own breaks

 

i to have a 97 f150 that had the same problem all i had to do to it was adjust the rear brakes as the rear brakes are pedal height once i adjusted the rear brakes my pedal came right back to the top

 

I have seen a few ABS units cause this problem. The dump valve gets stuck and all the brake pressure gets dumped into the accumulator. Make some plugs for the master cylinder and plug both ports. The pedal should be rock hard and not move more than an inch. If it does move then the problem is in the master cylinder or booster. If it does not move then the problem is the ABS unit.

 

Ok here is my problem, on my 1999 4x4 it has been twice that im going around 5 to 10 mph and when trying to brake my pedal gets blocked or just stuck at the top doesn't go down at all, my brakes sound like metal to metal grinding and pressing and releasing the pedal several times get rid of the problem. The first time it happened i was so woried i went straight to the brake shop and got all the brake pads replaced. My abs light has turned on a few times after that but i have not felt that terrible grinding any more. Allso my brakes have never worked the way the peddal is always low and when i slam on them the abs kicks in but the truck doesn't stop fast enough i dont trust my brakes. so far i changed only pads rotos and discs. Some one has experience this or has suggestions

 

I'd check for a bad wheel bearing assembly. If they get too worn, the hub lays over a little bit and the wheel speed sensor doesn't get a good reading from the tone ring, and, the PCM then thinks that wheel has stoped turning and initiates the ABS.

 

Ok great thanks for the advise pdqford