The pedal went to the floor and if I pumped it I could get a little back pressure?

1998 DODGE DAKOTA

85,000 MILES • V8 • 2WD • AUTOMATIC

CANMAN1969

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I replaced all my brake lines 6 months ago and last night coming home from work my ABS and brake light came on when I pushed the brakes. The pedal went to the floor and if I pumped it I could get alittle back pressure. I restarted and the lights were off until I hit the brakes again. I see no leak and the Brake fluid level is not low.

Jan 20, 2008 at 11:54 AM

SQM

CERTIFIED EXPERT
6,383 POSTS

Hello,

It sounds like you might have a faulty brake master cylinder.
When a master cylinder unable to build pressure, the brake pedal will go to the floor. Sometimes you can pump it up for momentarily before loosing brake pressure again.
This usually happens when the seals inside of the master cylinder blows out.

Another item you need to check is the brake booster. If the vacuum assisted booster have issue it can trigger similar symptom.
Make sure that the vacuum gauge is connected securely to the booster.
You can also test the booster by using a vacuum gauge (see diagram).

If you were to change out the master cylinder, be sure to bleed the brake system afterwards.

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

I have attached the diagrams for your reference.

Please let me know of any questions.

Thank you.

Images (Click to enlarge)

Aug 19, 2021 at 10:48 PM