02 brake pedal goes to the floor

I have a '02 with long time brake issues. For the past month or so the pedal would go almost to the floor before stopping. I could pump it up a little with the key off, but once I started the truck the pedal dropped almost to the floor. No leaks and no fluid loss. It would stop, so we let it go. This week I noticed a little fluid below drivers door. Replaced brake line and bled brakes. Hoped to fix the pedal issue. No such luck, pedal still the same. I have since replaced the master cyl. I bench bled prior to install and bled brakes after. Pedal still the same. From what I am reading, this is not typical symptoms of booster issues. Aside from brake light during bleeding, no ABS or other codes. What should I look at next. Thanks.

Have you bled out the entire system, or just the cylinder?

Sounds like a cylinder issue.

I have a '02 with long time brake issues. For the past month or so the pedal would go almost to the floor before stopping. I could pump it up a little with the key off, but once I started the truck the pedal dropped almost to the floor. No leaks and no fluid loss. It would stop, so we let it go. This week I noticed a little fluid below drivers door. Replaced brake line and bled brakes. Hoped to fix the pedal issue. No such luck, pedal still the same. I have since replaced the master cyl. I bench bled prior to install and bled brakes after. Pedal still the same. From what I am reading, this is not typical symptoms of booster issues. Aside from brake light during bleeding, no ABS or other codes. What should I look at next. Thanks.

If you have bled the entire system and are not getting any air, you may have to have a "automated bleed " done on the ABS valve. This can only be done with a capable scanner, like a Tech2. Afterward the system will need to be bled again manually. A few ABS stops (done safely of course, dirt road would be great!) may help purge air from the ABS unit also. If none of these help, it's quite possible there is a problem internal to the ABS unit (BPMV) causing some internal leakage.

This sounds like something that happened to my first car (89 Honda Accord). The master cylinder blew and after replacing it the brakes never felt the same. I had it done at meineke just because there was one right down the street and the handbrake still worked. When it was done the pedal felt different. It was still easy to push but I would have to push it further to actually use the brakes. The brakes worked fine, I just had a hell of a lot more pedal travel. I took it back to meineke and they bled the brakes again for free and it changed nothing. Thinking maybe they f*cked up I did some research, bought a shop manual and did it myself... twice. Same thing, the brakes were there, this time I saw the pads and they were fine and they worked great but there was just a lot more pedal travel. Eventually I just gave up on trying to reduce the pedal travel and got used to it.

I bled the Master then the entire system. Very little air and no change to the pedal. I can try the ABS gravel road bleed but I thought I would have a code if that was needed.

I bled the Master then the entire system. Very little air and no change to the pedal. I can try the ABS gravel road bleed but I thought I would have a code if that was needed.

It will not set a code if air is trapped in the BPMV.

What type of booster, Hydro or vacuum?

It's vacuum. Could it be the booster?

It's vacuum. Could it be the booster?

on your problem there could be some air trapped in the system. brake fluid leaking under the driver side frame rail area is a GM defect with how they mounted the ABS valve system and those defective lines.

it is possible after you bench bled the system air got back into the master. rather than remove master , bleed master on vehicle . remove the lines from the master then install with the bleed fittings use clear vinyl 1/4 tubing into the fluid of the res of the master. see if you have some air , if so then that maybe why it causes the pedal to be lower than normal since air compresses a lot compared to a liquid.

when the brake pedal is depressed slightly no fluid will leak out the master so when removing the master brake lines little will leak out.

bleeding is a tough job with no power bleeder. try to use a air compressor powered bleeder . like harbor freight has for about $30 item #92924,,,. vacuum bleeder is good for small bleed jobs .

with the ABS 60A fuse installed and you had leaks air in system the ABS may have air in the abs pump system of the BPMV...
as was mentioned ABS activation a few times may get this to help the low pedal.

pedal to floor is usually the master but with leaks a lot of air trapped. new master may not mean good master cyl.. might not be pumping enough fluid .

then you must also check for the rear brake line next to gas tank .. it leaks there on all these vehicles and does not reveal most times by drips on the ground ..

post back what you did. GOOD LUCK..

Would it be possible to plug one of the lines at a time leaving the master cylinder and then check the pedal? Thinking this might eliminate the master and booster and also lead me to which brake lines might have a pin hole. Or would I be creating more issues?

Would it be possible to plug one of the lines at a time leaving the master cylinder and then check the pedal? Thinking this might eliminate the master and booster and also lead me to which brake lines might have a pin hole. Or would I be creating more issues?

the booster leaking vacuum will cause a hard pedal . when you push down on the brake on a cold start does the pedal drop down easy ? if so the booster is good not leaking.

remove the brake line at the master , with the brake pedal slightly down. this will prevent the fluid from leaking out the master cylinder .. connect a hose from that port into the res. fluid so its in the fluid. I would do the port closest to the front bumper that is the rear brakes. as you pump the brake pedal slowly see if its with bubbles . if so then the rear must have a leak somewhere. like the gas tank frame rail .. with drum brakes you may have to remove the drums.

the port closest to the fire wall is the front brakes .repeat doing this port also observe for bubbles.

block off the 2 ports with plugs push down on pedal see if it holds . if so then the master is good. if it drops down and the plugs do not leak then the master is crap.

post back what you screwed up !