Brake Pedal Goes to the Floor!!!

[makaveli3004]

2013 Ford Edge Se V6 Brake pedal goes to the floor and I can barely stop. I replaced the brake booster 1.5 years ago and it was clearly the issue at that time as you could hear hissing, the engine would revv ect. This time I have none of that. Car sounds and drives fine expect the pedal is so squishy it goes to the floor. I can pump the brake and it starts to gain pressure then disappears again. This was an intermittent issue that would last a day but fix itself. This time it's not. I purchased a scan tool to bleed the ABS but this did not work. I also tried driving fast in a dirt field and slamming on the brakes to engine the ABS. ABS engages but still no brakes. My gut tells me it's the HCU but I don't want to spend a ton at the dealer to test things only to find out it was something easier. My pads all look okay and were changed less than 10k miles ago. I also went through each scanner tool component and heard the on off sounds from the abs except these two right rear dump and left rear dump produced no sound.

Edited June 11, 2025 by makaveli3004

[Wubster100]

Welcome to the forum @makaveli3004!

What is your model year?

[makaveli3004]

2013

 

 

 

[invisible_squid]

I had this happen to me. The first time it happened was immediately after an ABS event. The pedal would go almost fully to the floor, except it would build pressure and actually brake near the bottom of the travel. Felt almost like the master cylinder was bypassing until the very last minute.

Took it to a local dealer, who first diagnosed it as a faulty brake booster. Which does not make sense at all. If the booster was failing, the brakes would be harder, and I would see the revs jump up from the vacuum leak, and I was getting none of that. I told them to test and check the HCU because a tech I was friends with said it sounded familiar.

In the end, what was happening was that the ABS HCU bypass valve was stuck open, allowing pressure to flow into and fill the accumulator before the system gained any pressure. When they replaced mine, they didn't bleed it properly, so the system was still full of air, making it seem like the problem was still there. They forced me into giving them authorization to change out the booster, too, which would mean they'd have to bleed the system twice. Haven't had any issues since

[enigma-2]

I had this happen to me as well. Too it to the dealer and he also diagnosed the problem as a faulty brake booster (which they replaced under extended warranty.) I finally got it fixed by taking the car in and had them do a full brake job, and a brake fluid change (which also necessitated resetting the ASB HCU valve.) This fixed it. (Actually, by getting a  brake job, I got the brake "certified" technician, not just the jack of all trades technician. He knew exactly what was wrong. (Something about using the computer to cycle the valve.) Anyway, that fixed it and have had hard, high brakes ever since.

 

The ABS HCU bypass valve is a known failure point that can stick open and show up as a soft brake pedal or even goes all the way to the floor. (This can get real exciting, really fast.) If a dump valve is stuck open, brake fluid is continuously bypassed into the low pressure accumulator, rather than being sent to the calipers. This causes the brake pedal to drop to the floor.

 

.

 

Edited yesterday at 06:24 PM by enigma-2