Super Duty ABS/HCU symptoms

[Kevin 007]

What are the symptoms of a failing/failed ABS HCU unit? (99-03 superduty)

Im having a tough time solving a soft pedal/pedal goes to the floor issue with a 99. New calipers, lines and hoses all the way around (no leaks anywhere). New master cylinder (bench bled). Bled several bottles of fluid thru the system via gravity, vac and two person bleed method. No air left in the system. Bled the ABS unit via Forscan, bled it several times, then bled the brakes again. Still having a soft pedal. Once the pedal gets about 3/4 of the way down it starts straining the hydroboost. Not sure how or why its doing that but it is. Tried a used, known good master and no difference.

Im thinking either a failed ABS HCU or possible hydroboost issues. Neither of which presented ANY issues whatsoever prior to doing the brake job.

Any thoughts?

 

[greenskeeper]

how does the power steering react when on/off the brakes? during the pedal loss?

 

[Kevin 007]

No problems whatsoever when im off the brakes.

I will be replacing the HCU tomorrow (hopefully) and will post results.

 

[greenskeeper]

No problems whatsoever when im off the brakes.

I will be replacing the HCU tomorrow (hopefully) and will post results.

Do you loose power steering when on the brakes?

 

[Kevin 007]

No I don't.
Replaced the HCU last night. I think that may have done it....I need to bleed some more (waiting for a second person)

 

[Kevin 007]

Yup the replacement HCU did the trick. I did have to bleed it a few times, via Forscan. But its all back to normal now, thanks