2003 Ford F-250SD 6.8 V-10 (Brake Pedal Goes To Floor)

Brian Diagnostician Idaho Posted   Latest   Edited  
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Braking
2003 Ford F-250 Super Duty Lariat 6.8L (S) 6-spd (S6-650)
Brake Pedal Goes To Floor

Hello, working on a 2003 Ford F-250SD 6.8 V-10. Brake pedal goes to floor. Replaced master cylinder with same results. Has anyone seen the ABS module go bad and cause these issues?

Thanks, 

Brian 

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Interesting
Diego Technician
California
Diego
   

Personally yes on a Ford of that vintage. actuate the pump through your scan Tool while somebody taps the valve block with a screw driver, your pedal will probably stay up. You may also try bleeding through the scan tool if it supports it, it rattles the valves for any air. wow pretty hard to type on this forum on mobile. It’s a little more intricate than what i wrote but if you can’t get it…

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Randy Diagnostician
California
Randy
 

Hello. Did you bleed the master cylinder? Bleed the HCU? You have air in the system. These Ford SD can be a pain.

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Steven Owner/Technician
Illinois
Steven
 

Second that. Ford vehicles of this vintage can be a real pain to bleed after changing master cylinder. It’s a job I hate to see come into the shop. Certain models ( Ford Escape Hybrid) are not able to be bled properly without dedicated specialized equipment. Master cylinder does not move as much fluid as you would think on some models. If you’re using conventional bleeding methods and starting…

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Paul Mechanic
Illinois
Paul
 

Always plug mc ports when chasing low pedal. Should feel like pressing on a brick if Master cylinder is good- then you move on. In the event you already have changed master cylinder, same thing, go ahead and disconnect lines and block off which is the same way I bench bleed. Just keep short stroking it till it will only travel about a quarter of an inch. Then you just mount it, connect lines…

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Stuart Mobile Technician
Illinois
Stuart
 

It could be the new master cylinder.I have had brand new ones go bad right out of the box. One I couldn't even bench bleed. That's why I won't install customer supplied parts anymore.

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Randall Owner/Technician
Michigan
Randall
 

Need more info on “goes to the floor”. In this era we faced customers who thought that because they could push the brake pedal to the floor, standing still at idle, there was a problem. Yet when you drove these vehicles down the road, if you attempted to duplicate the same effort on the brake pedal to get it to “go to the floor”, you would be in 4 wheel lockup. Had a lot of complaints about…

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Rusty Owner/Technician
Massachusetts
Rusty
 

Foundation brake issues are the most frequently overlooked cause of pedal mush. I‘d clamp off brake hoses first to see if you get “high n hard” Pedal bleeding is sometimes a futile venture. See if you can borrow a pressure bleeder.

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Mark Engineer
Colorado
Mark
 

Rusty If a person is getting ready to replace the hoses probably ok to clamp them off for testing. I thought I remembered each of the brake OEM advising against clamping hoses. Has that recommendation changed? I’m not sure because I’ve haven’t stayed current on the topic. Maybe someone with an instruction sheet can chime in to share facts with all of us.

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Rusty Owner/Technician
Massachusetts
Rusty
 

Did it for ions with no I’ll effects.

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Darren Owner/Technician
Arkansas
Darren
   

Brian, Don't forget to take a good look at the brake calipers and pads for abnormal movement and wear. I have seen all to often where a binding pad, caliper slide, partially de-laminated pad have caused the same thing. Also (and I chuckle every time I remember this one) by chance did some one swap calipers side to side? Just recently I had a 48 Studebaker truck with a disc brake conversion in…

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Chris Owner/Technician
California
Chris
 

Yes Brian there was a test to pull 2 plugs off the abs unit and check stroke using paper clips or a couple of small screwdrivers, they were kinda common at the time to cause low pedal.

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Danny Technician
California
Danny
 

I'll second what Chris stated about pulling the 2 plugs off the abs unit and checking the dump valves for movement. This one was from a 2005 E-150

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Helpful
Brian Diagnostician
Idaho
Brian Update
 

Thanks everyone for the information. I will take a look and see what I can find.

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