ABS Control Module/Hydraulic Control Unit R&R

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kythri

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ABS Control Module seems to have failed - constantly running the pump with engine off/key off.

Was planning on just swapping the module from the assembly I picked up at the yard, without removing the entire HCU, but an overly torqued T20 screw on the module stripped out, and it's not coming out without me pulling the whole assembly.

There's 5 lines in the HCU - two of them come off of the master cylinder, one runs back (assuming it splits at the rear axle) and then two more, which I haven't fully traced, but assuming the hit the two front wheels.

Are there any gotchas here, other than the fact that I'll have to bleed the damned system when I'm all done?
 
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kythri

kythri

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Well, no gotchas. Just had to make sure to stuff plenty of rags to catch dripping brake fluid.

New module/HCU assembly installed and everything seems good - error indicator went away. Haven't re-scanned yet, but not quite finished. Need to fill the brake fluid and bleed, but that's a project for tomorrow.

Ratcheting line wrenches - going to need to invest in some of those. Would have made this job SOOOOO much easier/quicker.
 

GaExpedition

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I'm glad you posted this. My pump started doing the exact same thing a couple months back and I just unplugged it. My only question is, did the computer recognize the new part with no issues? If not, I'm gonna grab one from the junkyard on my next trip. Because I unplugged mine, I have no cruise control.
 
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kythri

kythri

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I haven't booted up AE to rescan yet, but the ABS light that illuminated when the other pump crapped out did automatically go out when I hooked everything back up and started the engine.

When the pump failed, I didn't unplug the module, I just pulled the 50A FMX fuse from position 102 located in the under-hood fusebox (see page 166-167 of the 2000 Expedition owners manual here: http://www.motorcraftservice.com/?link=002&urlfile=/pubs/content/~WOYEXD/~MUS~LEN/41/00exdog1e.pdf - fuse is listed as "Four Wheel Antilock Brake Module")

I didn't lose cruise control after doing so - in fact, I had read that some people did, so that's something I specifically tested, as I drove around for about a week with the fuse pulled.

Conceivably, one doesn't need to pull the entire pump out to replace the module - the module itself is fastened to the pump with (4) T20 Torx screws, and if you can remove all of those, then you could just pull the module off the pump and swap, and avoid having to bleed the brake system like I'm going to have to do.

I will say, however, that getting to one screw is rather diffcult, given the placement of the master cylinder - this is the one that I managed to strip out.

If I had things to to over again, I think I'd try things in this order:

Unbolt (3) 13mm bolts holding pump assembly to body, allowing unit to be adjusted, likely allowing clearance for screwdriver to remove pesky screw.

A 20" long 3/8" drive extension will come in incredibly handy for two of the bolts, and a 13mm wobble-socket will help immensely for the bolt located, again, almost directly under the master cylinder.

Once removed, there should be enough play in the brake lines.

If you have to remove the entire module, I found it to be far easier to disconnect the two "feeder" lines from the master cylinder at the master cylinder, and transfer them to the new pump assembly outside the vehicle, then re-attach the other lines once the assembly is re-installed.

Don't forget to label the left/right brake lines accordingly, so you reconnect them back to the same inlet/outlet on the pump.

The rear brake line is a different size fitting, so it's obvious where it goes, and the feeder lines from the master cylinder are also two different sizes, so if you don't remove those from the pump assembly, you'll know exactly where to re-attach them to the master cylinder upon re-installation.

I'll likely bleed the brakes this Friday, and test out my new MityVac thinger. I had planned to do that today, but had to run a few errands, and got sidetracked by starting disassembly of this:

duster_1.jpg
 
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