# F-150 Brake problem

**URL:** <https://community.cartalk.com/t/f-150-brake-problem/55743>\
**Category:** Maintenance/Repairs\
**Tags:** brakes, ford, f150\
**Created:** [September 29, 2010, 3:54pm UTC](https://community.cartalk.com/t/f-150-brake-problem/55743 "2010-09-29T15:54:16Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![tomhhh](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tomhhh/32/1667_2.png) [@tomhhh](https://community.cartalk.com/u/tomhhh)\
**Post date:** [September 29, 2010, 3:54pm UTC](https://community.cartalk.com/t/f-150-brake-problem/55743/1 "2010-09-29T15:54:16Z")

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Hi everybody. My sister in law has an '01 F-150 4x4 with disc brakes all around that had a fading brake pedal. The brakes seem to be working ok but the pedal slowly goes to the floor with the motor running or not. I naturally replaced the master cylinder, but it did the same thing. Thinking I got a bad unit I took it back and got another one and installed it. You guessed it, same thing. I cant find any leaks anywhere, no indicator lights, no vibration. Im confused. Ive done many brake jobs and this is the first time Ive run into this. Any thoghts? Thanks.

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**Author:** ![researcher](https://avatars.discourse-cdn.com/v4/letter/r/edb3f5/32.png) [@researcher](https://community.cartalk.com/u/researcher)\
**Post date:** [September 29, 2010, 4:40pm UTC](https://community.cartalk.com/t/f-150-brake-problem/55743/2 "2010-09-29T16:40:39Z")

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Does this truck have ABS? If so you might have a problem with the hydraulic module. Verifying that the leak is in the unit will be difficult. Throwing a part at it will be expensive.

Let us know how this comes out.

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**Author:** ![Rod-Knox](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Rod-Knox](https://community.cartalk.com/u/Rod-Knox)\
**Post date:** [September 29, 2010, 4:52pm UTC](https://community.cartalk.com/t/f-150-brake-problem/55743/3 "2010-09-29T16:52:37Z")

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Remove the brake lines from the master cylinder and plug the outlets. Pump the pedal several times and then hold constant pressure on it for a minute. I once found 12 new voltage regulators to be defective.

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**Author:** ![tomhhh](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tomhhh/32/1667_2.png) [@tomhhh](https://community.cartalk.com/u/tomhhh)\
**Post date:** [September 29, 2010, 5:14pm UTC](https://community.cartalk.com/t/f-150-brake-problem/55743/4 "2010-09-29T17:14:02Z")

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yeah its got ABS. No ABS light on the dash. I will try the plugging the lines if I can find something to plug them effectively. I hate to give it back to her without it being fixed. Thanks for the ideas.