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Brake pedal goes to the floor

Tiny
BLAKEMCMILLEN
  • MEMBER
  • 2010 JEEP WRANGLER
  • 3.8L
  • V6
  • 4WD
  • AUTOMATIC
  • 85,000 MILES
Nine weeks ago my brake pedal went to the floor. I took it to the dealer they worked on it for nine weeks and have replaced the following:

Master cylinder four times.
ABS pump one time.
ABS module one time.
Front calibers one time.
Brake booster one time.
All four flex brake lines one time.
Bled system seven separate times.

The dealer gave the Jeep back to me and the brake pedal still goes to the floor. It will stop but not as well as it did before the pedal went to the floor.
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Saturday, January 19th, 2019 AT 10:41 AM

16 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon,

Did the dealer bleed the ABS module with a scan tool?

Did they pressure bleed the system?

They have missed something here.

Roy

ANTILOCK BRAKE SYSTEM BLEEDING

The base brake's hydraulic system must be bled anytime air enters the hydraulic system. The ABS must always be bled anytime it is suspected that the HCU has ingested air.

Brake systems with ABS must be bled as two independent braking systems. The non-ABS portion of the brake system with ABS is to be bled the same as any non-ABS system.

The ABS portion of the brake system must be bled separately. Use the following procedure to properly bleed the brake hydraulic system including the ABS.

NOTE: During the brake bleeding procedure, be sure the brake fluid level remains close to the FULL level in the master cylinder fluid reservoir. Check the fluid level periodically during the bleeding procedure and add Mopar(R) DOT 3 brake fluid as required.

BLEEDING

When bleeding the ABS system, the following bleeding sequence must be followed to insure complete and adequate bleeding.

1. Make sure all hydraulic fluid lines are installed and properly torqued.
2. Connect the scan tool to the diagnostics connector. The diagnostic connector is located under the lower steering column cover to the left of the steering column.
3. Using the scan tool, check to make sure the ABM does not have any fault codes stored. If it does, clear them.

ImageOpen In New TabZoom/Print

WARNING: When bleeding the brake system wear safety glasses. A clear bleed tube (1) must be attached to the bleeder screws and submerged in a clear container filled part way with clean brake fluid (2). Direct the flow of brake fluid away from yourself and the painted surfaces of the vehicle. Brake fluid at high pressure may come out of the bleeder screws when opened.

NOTE: Pressure bleeding is recommended to bleed the base brake system to ensure all air is removed from system. Manual bleeding may also be used, but additional time is needed to remove all air from system.

4. Bleed the base brake system. See: Brake Bleeding > Procedures
5. Using the scan tool, select ECU VIEW, followed by ABS MISCELLANEOUS FUNCTIONS to access bleeding. Follow the instructions displayed. When finished, disconnect the scan tool and proceed.
6. Bleed the base brake system a second time. Check brake fluid level in the reservoir periodically to prevent emptying, causing air to enter the hydraulic system.
7. Fill the master cylinder fluid reservoir to the FULL level.
8. Test drive the vehicle to be sure the brakes are operating correctly and that the brake pedal does not feel spongy.
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
BLAKEMCMILLEN
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  • 9 POSTS
One thing I forgot to include is that with the engine off the brake pedal will go down half way and is solid. Press hard and the pedal will not move. Start the engine and while running and no vacuum to the booster the pedal is still solid. With the engine still running, connect the vacuum hose to the booster and then the pedal goes to the floor.
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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Good chance you either have air in the system or the booster is bad.

Roy
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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The Dealer told me that each time they changed out an item they bleed the whole system. I am on my second booster and the pedal still goes to the floor. Since 90% of the brake system has been replaced, I don't believe that it is a mechanical problem anymore but an air in the system problem. I ordered a scan tool so I will be able to bleed the ABS module. As soon as the tool comes in and during a day off I will bleed the Module and the brake system. I'll let you all know what happens. Thanks
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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Your welcome

Always glad to help

Roy
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
BLAKEMCMILLEN
  • MEMBER
  • 9 POSTS
Hello,

Finally a day off. I did a manual bleed and then a ABS bleed (with scan tool). No air in system. Brakes still the same, to the floor. Did a manual bleed and a ABS bleed three more times. Still no air but pedal still goes to the floor. Do you think the master cylinder is the problem? They told me that they put on three different ones. Could they all have been bad? Now, the only thing I can think of is a defective master cylinder. Any ideas?
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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I wanted to try one more thing, I ran the Jeep without the vacuum source hooked up. I drove the Jeep without vacuum to the booster. To get the Jeep to stop as with vacuum I had to use both feet and pressed on the pedal. To my surprise, to stop the same as with a booster, I had to press the pedal to the floor. That makes me think it is the master cylinder. Any ideas?
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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Yes it could be. Did they use new ones or rebuilt cylinders.

Roy
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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They told me that the master cylinder's were new.
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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Did anyone pull the wheels and inspect the pads and shoes to be sure there is nothing mechanical wrong?

Roy
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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One of the things that they checked was the rotors and pads, all was in good shape. New rotors and pads were installed last year.
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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Were the calipers moving freely over the slides? If you have a slide that is seized, it will not move and that will affect the pedal.

Roy
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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I was told that the calibers were checked and that was why they replaced the front ones. I will check the front and back ones too.
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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Sounds like a plan.

Roy
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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Put on the new master cylinder and the brakes are a lot better, does not go the the floor. Still not as good as my other JK (2007) but a lot better than from the dealer. I did a manual bleed, do you think I should do another ABS bleed? I was told that the master cylinder should be level during a manual bleed. My driveway slops down, I can't do the bleed in my garage. So, what I am asking, is it better to have the nose down or up while doing a manual bleed? All four calibers slide freely.
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Monday, March 15th, 2021 AT 1:29 PM
Tiny
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Yes, do the ABS bleed again.

You can bleed wherever you need to.

Roy
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Monday, March 15th, 2021 AT 1:29 PM

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