J5Murph

A couple months ago I noticed my brakes were kind of soft but didn't think anything of it and maybe it would fix itself. And then about 2 weeks later my ABS light came on. Got it scanned and replaced the master cylinder and brake booster. Replacing these did nothing but make me broke. I'm now almost 6 months later and my brake almost goes to the floor at a red light and I still roll a little once I'm stopped. I've tried bleeding the brakes and replacing brake fluid and it helped for about a day. I'm positive someone has had this problem before and I'm also positive someone has a solution. Anyone have a clue about what's going on here? Anything helps! Thanks!

Bullhorn

Check all your lines, did the master cylinder get bled? Is air getting in but fluid not getting out? Leaks anywhere? What codes did you have? Abs light off now?

J5Murph

I got a brand new master cylinder so I'm guessing it was bled, there was a lot of air before fluid came out when I was bleeding the brakes, the ABS light is still on, I don't remember the code but I did some research and it says to get a new ABS module.

Raybz

I'm guessing that air got into the ABS unit. Only way I know of to bleed the ABS is to have the pump running and open an aft line, then do a normal pedal bleed. Problem comes in that to have the pump running you need a high end bi-directional scan tool or a dealer/shop that can do the ABS bleed for you

Raybz

Found the full procedure WITH a capable scan tool

If equipped with the 4 wheel anti-lock brake system and the Hydraulic Control Unit (HCU) has been replaced or is suspected of containing trapped air; bleed the brake system using the procedure below. Conventional brake system bleeding cannot remove the air trapped in the lower portion of the HCU. If a spongy brake pedal is present and air in the hydraulic control unit is suspected, use the following procedure:

1. Bleed the brake system as outlined in the conventional bleeding procedure.
2. Connect a New Generation Star (NGS) tester or equivalent scan tool, to the serial data link connector below the instrument panel as though retrieving codes.
3. Make sure the ignition switch is in the RUN position.
4. Follow the instructions on the NGS screen. Verify correct vehicle and model year go to the "Diagnostic Data Link' menu item, choose ABS Module, choose "Function Tests", and choose "Service Bleed."

5. Bleed the right-front wheel as follows:
---A. Open the caliper bleed screw and pump the brake pedal for 3 seconds. Repeat the procedure again.
---B. When the fluid runs clear, begin the program and continue to pump the brake pedal.
---C. Continue bleeding for approximately 1 to 2 minutes after the program ends and then tighten the bleed screw.
6. Repeat the bleeding procedure to the left-front, left-rear and finally the right-rear wheel.
7. Remove the pressure bleeding device and adjust the brake fluid level.
8. Road test the vehicle and check for proper brake system operation.

serranot

https://www.f150forum.com/f6/brake-p...-150-a-157374/

You can check this with a paper clip and 30 seconds.

TRD-Toy

It's the HCU. If you put on a master cylinder and there is no leaks. It's internal problems with HCU. I have put so many of these on in the past month. Sounds like you may need the whole unit to fix the ABS light too. It's not cheap to fix, just a heads-up.

J5Murph

Well I'll be honest I'm selling the truck once this is done so I'll be doing the bare minimum I can get away with to fix this.

02_Black_On_White

You didn't bench bleed the MS. They don't come pre-bled, needs to be filled, ports opened and the cylinder needs to be cycled until it becomes to hard to push. You literally forced air into your brake system.

UtahGuy

^ Yup.

I had this trouble a bit ago. I read in another thread that spongy brakes that still keep you stopped at the light is a bad HCU (the test serranot is pointing you to), and spongy brakes that gradually start creeping after you've come to a stop are a bad master cylinder. You probably fixed the original trouble, but you have to bench bleed the master or you'll never get all the air out of the lines.