changed the brakes and the master cylinder the pedal still goes to the floor

Chances are your truck has four-wheel anti-lock brakes. If air was allowed to get into the steel lines, it will have collected inside the ABS hydraulic controller. A scanner is needed to command the computer to open two valves so those chambers can be bled. The entire procedure takes all of about 15 to 30 seconds, and will typically require bleeding the two right wheels. The correct instructions will appear on the scanner's screen and in the guide below.

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

and

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Please run down this guide and report back.

how do i bleed the air out of a 2009 dodge ram abs? I have spent several hours bleeding the abs, and pedal still goes to floor. I have bled each caliper and the abs block. WHAT else do i need to do?

Check the brake master cylinder could be leaking internally giving you the sink to the floor problem. These videos and guides can help us fix it.

https://youtu.be/w7gUsj2us0U

and

https://youtu.be/WDxvEQrMkBg

and

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Please run down these guides and report back.

Ok here what happened, I took my calipers off the truck without depressurizing the system first.I have bled each caliper and bled the rwal and abs block, so I used a scanner to open the ABS valve worked great!

Nice work, we are here to help, please use 2CarPros anytime.

My ABS light and brake light are both on. I have put new pads on all four wheels. I changed the master cylinder with a rebuilt one from the auto parts store, and I changed the rear ABS sensor as that was a code the computer was putting out. The biggest problem I have is that when the truck is not running, the brake pedal seems to be full but as soon as the master cylinder reservoir was always full and there are no leaks.

Did you bleed the master cyl on the bench and did you do a full brake system bleed? sounds as if there is air trapped in the system still.

Yes, I did a bench bleed on the new master cylinder, and I did a full system bleed 4 times. I've never had this problem doing brakes before. I'm wondering if there is a chance that there is air caught in the ABS unit and, if so, how to get it out. I have full pedal when the truck is off but as soon as I start it up, the pedal goes to the floor.

Yep air can get stuck inside the ABS system in which case you will need a shop to use their scanner to open the valve while bleeding the system.

Please let us know what happens

Cheers, Ken

I had to replace the AC condenser fan motor which required me to remove the battery, battery tray wheel well, etc. There is a part of the ABS mounted on the battery tray behind the battery which I had to remove the screws from the tray to remove the tray. I never disconnected it or hit it with anything. it pretty much stayed in the same position as it was when bolted to the tray.
I got this all done and the truck back together when I got in the next morning the brake pedal went down to the floor on me. it has never done this before and I have new power stop pads, cylinders and drilled & slotted rotor all around plus new master cylinder. They are about 2-3 years old. The brakes worked perfectly prior to doing the fan motor.
Before I go through the process of bleeding anything or opened up the brake lines in any way I'd like to know if there is a possibility that just moving the ABS component could have anything to do with this issue? would the ABS actually be able to cause the brake pedal to get mushy outside of any leaks which there are none anywhere. top to bottom, front to back. I checked everything twice.
Thank you for your assistance on this. I can't afford to take it to the dealer or any mechanic.

Hi,

If nothing was opened, then you should have a the same brake pedal. I assume the brake fluid isn't low. In a hydraulic system like this, if the pedal goes to the floor and there are no leaks, (and nothing has been opened to allow air into the system) the master cylinder has to be bad. The chances of it happening when you worked on something different are slim, but nothing else makes sense.

Here is a link covering possible causes, but it sounds like you have already checked everything:

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

I am going to provide the directions for bleeding the ABS, but I can't see how that is the problem. Here are the directions which do require a scan tool:

______________________
2007 Dodge or Ram Truck RAM 1500 Truck 2WD V8-5.7L VIN 2
ABS Brake Bleeding
Vehicle Brakes and Traction Control Hydraulic System Brake Bleeding Service and Repair Procedures ABS Brake Bleeding
ABS BRAKE BLEEDING
ABS BRAKE BLEEDING

ABS system bleeding requires conventional bleeding methods plus use of a scan tool. The procedure involves performing a base brake bleeding, followed by use of the scan tool to cycle and bleed the HCU pump and solenoids. A second base brake bleeding procedure is then required to remove any air remaining in the system.

1. Perform base brake bleeding.
2. Connect scan tool to the Data Link Connector.
3. Select ANTILOCK BRAKES, followed by MISCELLANEOUS, then ABS BRAKES. Follow the instructions displayed. When scan tool displays TEST COMPLETE, disconnect scan tool and proceed.
4. Perform base brake bleeding a second time.
5. Top off master cylinder fluid level and verify proper brake operation before moving vehicle.

Let me know.
Joe

Thank you for your advice. At this point I am pretty much ready to clear myself of any wrongdoing and chalk it up to coincidence as tough as that is. I bought the master that is on there now in July 2017 right after I bought the Power Stop Calipers and rotors all the way around. They claim what they sold me was a Raybestos brand. I've heard of them going way back so I assumed they were a good product and maybe they are. I bought it on Amazon which I've discovered is usually hit or miss.
I'll look over the information you included. Is there anyway to test the ABS or does that require a shop with the right scan tools? (I'm wondering if anyone rents them?) I guess this still bugs me that I'm having this problem immediately after doing the other work which I did have to unbolt and move the ABS around to get the battery tray out. Plus I'd hate to put in a new master cylinder to have it keep going to the floor. But as you said the only thing it could be with the fluid level not dropping at all is the master. I guess I'll need to replace it soon anyway because I've had to drive it around a few times and the pedal doesn't have a block of wood to keep from dropping too far.Pumping it does absolutely nothing at all which seems strange as well.
Thanks again. I'll let you know if it turns out the RAM has some strange powers that makes it run different than other vehicles. Ha

Allow me to add a note of great value. Too many people think you have to bleed at the wheels after replacing the master cylinder. That pushes air down the lines, and on about 50 percent of vehicles with ABS, that air gets stuck in two chambers of the hydraulic controller. A scanner is needed to command the ABS Computer to open two valves so that air can be expelled, then you have to complete the procedure by bleeding that air out at two wheels.

Instead, when you replace the master cylinder with two steel lines, loosen the line nuts a little, remove the mounting bolts to the power booster, pull the master cylinder forward, then use it as a handle to bend the steel lines up a little. That will keep the fluid from running out of the lines.

Remove the two lines all the way, then remove the master cylinder. Brake fluid eats paint, so be careful to not allow any to drip onto the car.

Screw the two lines into the new master cylinder that has been bench-bled, then use it to bend those lines back down to their normal shape. Bolt it to the booster, then snug one of the line nuts. Have a helper slowly push the brake pedal half way to the floor. It should take about 15 seconds to do that. You'll see bubbles coming out by that nut. Snug the nut, then holler to the helper to quickly release the pedal.

Do that a second time, and perhaps a third time, until you see only clear fluid with no bubbles coming out, then do that for the other line. By pushing slowly, fluid will get pushed down the lines, and air will float back up. By releasing the pedal quickly, the fluid rushing back will wash the air back up into the reservoir with it. This can even work when working on the car by yourself, just keep the line nuts tight.

Pedal is hard and high when not running. With engine running, pedal is spongy and sinks. Noticed when manual bleeding, that front calipers flex a lot.
New master cylinder, new vacuum booster, new front flex hoses, new front calipers, new ceramic brake pads all the way around. Also new front wheel bearing assemblies. Rear flex hoses and calipers are original. Rear calipers have new slide pads and pins.
Replaced ABS pump/manifold with junk yard unit.
I have bled and re-bled using various methods. Gravity bled, power bled, reverse bled. Also used scanner to bleed ABS.
If I clamp the front caliper hoses, the brake pedal is hard and high. Unclamped, it's spongy.
I've checked all the mounts and connections on the front, and can find nothing.
What is causing the flexing? Am I getting too much pressure to the front brakes? Can the ABS be causing this?
This all started, because I removed the rear caliper to repair the seized slide pins, and let the system bleed dry....

Good evening,

By doing the test you did, you have zeroed in on the issue. Make sure the slide pins are free and greased well.

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

You may also have bad calipers even though they are new.

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

Roy

I've had all the calipers on and off, more than once. I can't believe that both front calipers are bad. Especially since I had the same symptoms with the old calipers. All the pins and slides are brand new. I'm just hoping that the new, ceramic brake pads aren't seated to the old rotors. I'm going to drive it for a while (very carefully) and hope that the pads seat themselves and the pedal gets better. We'll see.

That is not the issue. The calipers themselves could be the issue.

I have to ask this question. Are the bleeders for the calipers at the top of the caliper? If the calipers are on the wrong side, the bleeders will be at the bottom and the air will never come out.

Roy

Bleeders are on top.
Like I said, problem was the same for both the new and old calipers.

With the hoses clamped off, and you had a good pedal, the issue is in the front wheels from the hoses to the caliper.

Roy

Brake pedal fades, no lights on the dash...replaced OE master cylinder twice Dealer wants to replace abs controller...controller or module. Can ABS cause brake fade. I have checked on vacuum leaks no external leaks. Can ABS cause brake fade without setting lights on dash?

Yes, ABS modulator can cause brake fade without triggering any trouble codes. These videos and guides can help us fix it.

https://youtu.be/w7gUsj2us0U

and

https://youtu.be/WDxvEQrMkBg

and

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Please run down these guides and report back.

the brake shop that replaced the master cly. 2 times said they blocked off the abs system somehow and determined that there was nothing wrong in the brakes that the problem was in the abs system. It doies act just like a master cly with an interna leak but with the abs system being all vac. I was not sure that it could act the same.

Th ABS system requires a DRB scan tool to perform bleeding apart from normal bleeding procedures, was this done?

If you pump the pedal quickley does it pump up to norrmal and then fade out ?

Thanks for the guides it was the master that was out

i have the truck listed above 1500 with rear wheel ABS only. the infamous brake line that goes from the front junction block to the rear hose/junction block blew out. i replaced the line and went to bleed the line by bleeding it out through both rear bleeders. starting at the right rear. i had a friend pump the brakes and hold pedal while i open the bleeder.after many repeats of this process no fluid came out. i then started the truck and did same process and after 1 time fluid came out. i bled all the air out so i moved to the left rear. bleeder screw was seized and i wound up snapping it off so i replaced the left rear wheel cylinder. repeated bleeding process and no fluid.started truck and repeated process and fluid came out. bled out all the air from both rears and pedal is still almost to the floor. when you start the truck no lights are on but after pumping brakes the brake and abs lights come on. i have read online about the proportioning valve and how it controls the rear brakes to prevent skidding and about using a scan tool to activate the valve etc. since the line i replaced was after the prop valve and rwal unit i don't see why i'd need to worry about bleeding them? i read that if the valve is off center in the prop valve it'll kick the brake and abs lights. master cylinder was never ran dry during any of the process. any suggestions? thank you

If you pump the brakes, do you get a pedal or is it still really low? If you hold pressure on it, will it slowly go to the floor? Are you sure the rear brakes are properly adjusted?

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Let me know.

Joe

If you pump the pedal it will build up but not much at all very minimum. If you hold the pedal it doesn't fade but it's just very low. Solid streams of fluid come out of the rear so i am wondering if there is something wrong with the rwal valve or hcu. but not sure how to test them.

If you weren't getting a solid stream from the rear, I would suspect an issue with the RWAL or the combination valve, but that isn't the issue. However, here is what to do if you suspect the combination valve. On the combination valve remove the center pressure differential switch and center the spool valve - then don't step on the brake until you try gravity bleeding the system until you get a drip out the back bleeders. Then bleed normally.

Since the brake pedal is going to the floor, I'm starting to question if the master cylinder has failed. I have seen (many times) when the brake pedal goes to the floor on vehicles with miles, the plungers in the MC go into a portion of the cylinder not used and are damaged by corrosion and dirt. The result is you may get a stream when bleeding the brakes, but the MC isn't strong enough to pressurize the system when it is closed.

Did you also bleed the front brakes?

Let me know.
Joe

Sorry for delay in response. it wound up being the master cylinder sucking air. so i replaced it and fixed the issue. Thank you to you all.

No problem and you are very welcome. Toward the end, I was suspecting it was related to the master cylinder. I'm glad to hear you got it taken care of and are up and running.

Please feel free to let us know if you have questions or need help in the future.

Take care,
Joe

Brakes problem
2001 Dodge Ram Two Wheel Drive Automatic 60k miles

I had a brake inspection done,due to the brake pedal sinking to the floor. The results of that said front brake pads are low ,and rear shoes low but neither in an emergecy situation. I was told and also as the report says master cylider needs replacing,due to floor going to floor. That was my hunch it was before going in for check. The brake pedal to floor started 2-3 days ago as i got in and noticed the pedal went right to the floor upon first brake depress.
I replaced the master cylinder,bench bleed it first and installed the new one in. Needless to say the brake pedal still goes to the floor and the ABS and BRAKE lights are stiill illuminated to. The pedal feels like it sinks to the floor at the rate as before,so i am thinking a brake bleed at the wheels would not make a huge difference at this point. Could it be with the brake booster? Thanks to all!

Brake booster may be the problem , What I would do is start with the brake master cylinder, make sure it has pressure when brake pedal depressed. then work to the abs system, bleed that, {have seen where there was air wass caught in the lines where they curved up. {learned that from my son} Then proceed to the rear brakes. It may take a couple of bleedings to get the air out. If that fails then look at the booster

Thanks for the reply MJ. I got it figured out.With some more investigation it proved to be a defective master cylinder right out of the box. Exchanged it out at the auto parts store,bench bleed the new master then bleed at all four wheels. Brakes work like new again! I like it when things work as they should!
Thanks

It happens occasionaly when they rebuild parts that they are bad. Have seen something brand new come out of the box bad.

i was driving and my front right caliper busted the seals and brake fluid leaked out of it and my whole front brake system failed and i had no brake pedal pressure at all and i was just driving with my back brakes only. i replaced both calipers,pads,rotors and bled the fronts only. now when the engine is not running when i pump the brake pedal there is some pressure but it slowly sinks to the floor and comes back up slow. when the truck is running there is absolutely no pressure in the pedal and it goes straight to the floor. but the back brakes are still working so could it be a bad master cylinder or could there still be air in the lines or something else? now the whole time the abs and brake lights stay lit on the dash as soon as i touch the pedal when the motor is running

There's two things to consider. First of all, the master cylinder can be damaged when you run the pedal to the floor. This often happens when the system is being bled with a helper. To avoid that, never push the pedal more than half way down unless the master cylinder is less than about a year old. Crud and corrosion build up in the bottoms of the bores where the pistons don't normally travel. When you do push them that far the lip seals can get torn on that crud. These videos and guides can help us fix it.

https://youtu.be/w7gUsj2us0U

and

https://youtu.be/WDxvEQrMkBg

and

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Please run down these guides and report back.

Second, on a lot of ABS systems you need a scanner to activate a couple of the valves to allow trapped air to bleed out. That is not a concern if the brake fluid reservoir never ran empty or if you have the rear-wheel ABS system. The scanner is needed for all-wheel ABS systems.

First I will start with what I know about my situation. There are no leeks, no air in the system. I have bled a gallon of fluid through it and no bubbles. I have replaced the master cylinder and the booster. I have tested three different ABS modules. The brake light and ABS light are on. It will build little pressure while the truck is off but when I start the truck I lose everything. PS: I bled the lines while it was running and while it was off. I am scratching my head, please help.

You likely have air in the ABS hydraulic controller. A scanner is needed to command the computer to open two valves so that air can be expelled, then bled out at the wheels.

front brake line blew all fluid came out replaict line filled fluid and blead have no pedal does master have to also and how?