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Old 06-10-2012, 09:19 PM   #1
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Default Brake Pedal Fade - 2002 F-150

I replied to a different thread about brake pedal fade, but would like to document my issue here as well in hopes that it helps someone else out.

Condition: Brake pedal fades to about 25% of its range of motion when stopping. The issue is most notable when slowing to a stop, it requires additional pressure to stop as the pedal fades to the floor. The truck will stop and hold. Also, the ABS works properly. When braking at speed or on the highway, the issue is hardly noticable.

Diagnosis: So far I have had the system bled twice, without much or any noticable improvement. The tech working on it says it's probably the master cylinder. I kind of agreed, however I thought if it were the master cylinder the system would leak all the way down, not stop at a point like it is currently doing. The technician working on my truck is my friend, he is knowledgable, however, he doesn't work on Fords all day. I called my friend that works at Ford to get his opinion. He says it could be a master cylinder and also he has seen the ABS hydraulic control unit (HCU) go bad, essentially causing some of the brake fluid to enter the ABS system under normal braking.

I did some research on the issue, it seems like a pretty common problem. It seems like a lot of folks with the problem replaced a few master cylinders before diagnosing the ABS HCU. Here are a couple of the links I found in my research.

---http://www.f150forum.com/f6/2001-f150-4x4-brake-pedal-fade-72205/index2/---
---http://www.justanswer.com/ford/4zx3a-2003-ford-f150-brake-pedal-the-hcu-hydraulic-control-unit-leak.html---

Today, based upon what I read, I checked the ABS HCU. The unit is generally located near the master cylinder, below the air filter. I removed the plugs off the two lower ports, on the firewall side of the part (the ports are below the brake lines, you will have to feel around for them). I fashioned a paper clip and inserted in the driver side port. While the truck was running (and me holding the clip), a friend slowly braked. The valve had at least a half inch of movement towards the firewall. Based upon what I have read, this is a sign of a bad ABS HCU.

This is what the ABS HCU looks like:
Top View
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Firewall side
Name:  HCU2.jpg
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The numbers on my part are:
Number/Code below bar code: TRW EHCU 13975507B (Not sure what this means)
Ford Part #1L34-2C346-AA

Ford price on the part lists for $710, fordparts.com has it at my dealer for $575. At this point, I am going to try and order a salvage unit from LKQ or on ebay. There is a parts seller on eBay selling new units, free shipping for $225 and comes with one year warranty. I saw one on LKQ for $150 that is a salvage and you could purchase up to 24 month warranty for a reasonable price.

Sorry for the length, I hope this helps someone out with this issue. I will post an update when I get the new part on my truck and the issue is resolved.
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Last edited by Jktx21; 06-10-2012 at 09:35 PM.
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Old 06-10-2012, 09:22 PM   #2
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See above
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Last edited by Jktx21; 06-10-2012 at 09:34 PM. Reason: See Above
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Old 06-20-2012, 09:58 AM   #3
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Great post! Did this fix your issue? I have a 2002 F150 FX4 SuperCrew with the same exact brake pedal fade issue. Would really like to know before I start down the path of replacing this.
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Old 06-20-2012, 10:10 AM   #4
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You've topped off your reservoir right? Mine when coming to a stop (anywhere below 15mph) hesitates and pulls slightly to the left. I'm thinking it might be a vacuum leak? I topped mine off and it helped a little

Last edited by hbc15; 06-20-2012 at 10:15 AM.
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Old 06-20-2012, 10:35 AM   #5
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I've gone through this truck from Front to Back. Bleeding brakes, Master Cylinder, Caliper Replacements, Complete fluid swap. Nothing works. Still the same gradual pedal fade while sitting at a light. I've seen a few posts on various forums all talking about the HCU being the issue. Wanted to see if in fact this really fixed his truck before I do the same thing.
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Old 06-23-2012, 02:47 PM   #6
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Replaced the ABS HCU this week, fixed the issue I described above. Good luck! Check those relief valves on the unit as described above!
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Old 06-24-2012, 11:46 AM   #7
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Awesome news! So did you end up getting one from the salvage yard or off of eBay? How long did it take to get it installed and bleed the system?
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Old 06-25-2012, 09:13 AM   #8
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I purchased a new part from eBay. I didnt install it, my tech friend did. Based upon what he charged me, I assume it took a couple of hours.
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Old 06-26-2012, 10:50 AM   #9
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Cool deal! Thanks for the responses! Looks like I'll be doing the same for my truck.
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Old 08-22-2012, 07:29 AM   #10
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Default Brake fade bad hcu

My hcu has also been diagnosed as faulty on my 2002 f150 and I am looking for alternatives rather than spedning up to $1000 to have it repaired by the dealer or local mechanic.

A couple questions I have is: Is it possible to just disable the ABS system and if not addressed is it possible for brake failure that could cause an accident?

The truck does stop but sometimes I have to pump the brakes for more resistance.

any help is appreciated.
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Old 08-22-2012, 07:29 AM
 
 
 
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