How to bleed the brakes with rear ABS?

1994 FORD RANGER
113,000 MILES • 2.3L • 4 CYL • 2WD • MANUAL
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GOGOJUICE6
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I replaced the master cylinder in my truck. According to Haynes, after bleeding master cylinder, I have to bleed the ABS unit. There's no bleeder screw in it, just an 7/8 nut,(which I don't want to mess with it, not knowing what is it for) and then, continue with the standard bleeding pattern. How do you bleed a screwless ABS unit, if so?
Thanks for your help, and
Happy Holidays to y'all.
Dec 1, 2024 at 6:34 AM
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STRAILER
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Happy Holidays to you as well. Can I ask if you have a good brake pedal, and the system seems to work okay? If so then you don't need to bleed the ABS system. The only way to bleed the ABS is with a scanner to open the valve inside the control valve. Please go over this video to show you what I am talking about:

https://www.youtube.com/watch?v=nQRnKyVyMuQ&t

Please let us know what happens.
Dec 1, 2024 at 12:43 PM
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GOGOJUICE6
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Brakes were fine until the right rear wheel started locking up. Thinking it was air in the line, bled it. Nasty dark fluid and air was coming out until it stopped. Maybe clogged line. Took it off and it is clogged. Ordered both sides, should be here by Thursday (hopefully). I'm not sure if my obd 1(it's a '94) can pick up brake issues. I was told I could bypass ABS, is this true? If so, how do I go about it?
Thanks for your help and knowledge, Ken.
Dec 2, 2024 at 9:06 AM
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STRAILER
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The ABS system will not make the tire lock up; I would not worry about the ABS system if you have good brake pedal. Here is a guide on what makes the brakes lock up, please go over it to help fix the problem:

https://www.2carpros.com/articles/a-comprehensive-guide-to-fixing-automotive-brakes-locking-up

Please go over this guide and get back to us.
Dec 2, 2024 at 10:12 AM
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GOGOJUICE6
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Great, I'll replace lines, check the wheel cylinder and check for grease leaks. Bleed and see how it goes. Will let you know in a few days.
Outstanding article.
Thank you so much for your help.
Dec 2, 2024 at 11:37 AM
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STRAILER
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You are welcome, thanks for taking the time to read it, most people just want the, "put a piece of tape on it that will fix it@!" style answers lol.
Dec 3, 2024 at 9:23 AM
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GOGOJUICE6
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I just replaced mc (bled it)wheel cylinders, rear brake lines, including center flex hose, shoes, flushed and bled system and brake pedal still goes down, almost to the floor. What am I doing wrong?
Thanks for your help.
Dec 19, 2024 at 10:32 AM (Merged)
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MECHTRIX
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might be time to replace the master cylinder.
Dec 19, 2024 at 10:32 AM (Merged)
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MECHTRIX
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or the brake booster. check those first. hope this helps, good luck.
Dec 19, 2024 at 10:32 AM (Merged)
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GOGOJUICE6
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Master cylinder is brand new.
Dec 19, 2024 at 10:32 AM (Merged)
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STRAILER
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Did you bench bleed the master, also how is the rear brake shoe adjustment? Please go over this guide and video,

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

and

https://www.youtube.com/watch?v=WDxvEQrMkBg&t

To help isolate the problem you can use vise grips with fuel line over the jaws to gently close down the brake flex lines on the front and rear of the system. Let me know what happens.
Dec 19, 2024 at 10:35 AM
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GOGOJUICE6
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Hi, Mr. KenL,

Didn't bench bleed master cylinder, because I read somewhere, you could bleed it while mounted on booster.
Thanks for the help and links.
Greatly appreciated.
Dec 19, 2024 at 1:42 PM
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STRAILER
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No problem that what we are here for, let me know how it goes, have a good weekend :)
Dec 20, 2024 at 9:23 AM