that's great, I have a friend with a power brake bleeder, I am going to try to get him to flush my brakes again even though the first shop I took it to assured me that there was no air left in the system.

 

I hope it works for you. BTW, I'm not so sure it was as much air as it was contamination in the old fluid!)

But, it's a cheap fix, I spent under 10 bucks to flush it myself. Good luck!

 

have you checked the abs hydraulic valve

 

I had a friend that works at the ford shop bleed the system through the abs pump and he said it sounded fine, and said if there was a problem in the abs system it should turn on the abs light. The abs works, I have intentionally got it to kick on to see if it would change things. there has been no change in the way the pedal feels for over a year, I am used to it now. I wish I knew what the problem was so I could fix it just in case I want to sell the truck someday.

 

for everybody who had made suggestions I wanted to update what has been going on with my truck, the brake pedal fade has been consistent for over a year now. Everybody that drives it swears I have air in the lines. after bleeding the brakes for the umpteenth time, I decided to try a brake booster, that didn't change anything.

I have a friend that has access to the online ford manuals and he found a test to see if the ABS HCU relief dump valve was bad (when the abs kicks in, this valve is the one that releases brake fluid back to the master cylinder creating the on/off brake pulse) It said to remove the rubber plugs on the back of the ABS unit and insert paper clips into the holes until they touch the valve, then while the truck is running firmly and quickly depress the brake pedal. if the paper clip moves out more than a quarter of an inch the valve is bad and the HCU needs replaced. when we went to remove the rubber plugs, one of them was already missing. we did the test, and the one that was missing the plug had pushed the paper clip out three quarters of an inch. obviously it had blown the plug out when the valve failed.

So essentially I had an internal brake fluid leak, as I stepped on the pedal half the fluid went to the brakes and half went right back in to the master cylinder. Now I am looking for an HCU I can afford to get my truck finally fixed. Thanks again for all of your help!

 

I have had the same issue for a while now and have replaced almost the entire braking system, but will flush the system today. Thanks for sharing that information.

 

my 2003 f150 4w/d has the same problem everyone is having,two NEW master cylinders from Ford, brakes fade right to floor, stops good in a panic then fade away , bleed brakes three times, nothing same o same o every time. So my question is who has ever fixed this problem, i see nothing on any site where it was actually fixed.only one guy took a spring out of the rabs valve?? the ford dealer says bad m/c, don't believe it too many guys , too many m/c changed ,so what is it ????

 

I replaced the AB block and it solved the issue.

 

Thank You !

 

Hi everyone

First want to thank Grandpa's1983 for starting this thread. I too have a 2002 ford f150 that HAD brake fade. The problem was the HCU. I first took it to the dealer who put in a new master cylinder. that did not fix the problem. After doing internet research I found this thread. I bought a new HCU ABS PUMP and module off of ebay and had my local mechanic put it in. Truck brakes are fine now.
My local mechanic was able to bleed the HCU with his computer. I got the HCU off off ebay for $211 and it cost me $290 to have it put in. the part number is 1L34-2C346-AA.

The dealer mechanic had no clue about the HCU going bad. I wonder if I would have ever gotten my brakes working right if it would have not been for this thread.

Good luck to everyone with this problem.

Ford Truck Enthusiasts Forums - jasonv11's Album: 2002 ford f150 HCU

 

.....reviving this post from a year ago......Does anyone know "what" it is that goes bad in the HCU valve? I wonder if they are rebuildable? I seem to be having this same issue. Can you get just the valve body by itself?

 

I've never seen any type of rebuild kit for the hcu and they don't seem to be serviceable, finding one used seems to be the most economical choice, although I'm sure they will go bad eventually too.

 

I will be calling around tommorrow to see if I can get one used. If I do and it works, I will be cracking open the old one to see whats goin on inside. I did the test tonight and pulled off the cap on the drivers side port and stuck the paper clip in there and it pushed it back almost a half inch towards the firewall!! What is it that is pushing that valve back?

 

I'm not sure, I couldn't take my old one apart because we had to put it back on the truck we robbed the good one off of I mean borrowed, yeah that sounds better! it was a junk truck going to the scrap yard but had to be complete.

 

...bump....reviving this post again....we almost at 2 yrs with my truck still having this problem... I did buy a used HCU unit about a year ago....still the same thing...I also (due to rust), replaced all the rear lines from the front frame rail, all the way back to the calipers.....Still the same!! GRR...I am wondering, when I bought the used HCU unit, i only switched out the bottom portion with the valves....i didn't switch out the top electrical portion...Is THAT where the problem lies??