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I'll be replacing rotors, calipers, and soft lines at all four corners next week. I know if I were just purging some air I could bleed the brakes like normal, but since I also want to flush as much of the old fluid out as possible I might need to bleed the ABS valve assembly as well. From what I understand, you need a special tool from the dealer. Is this still the case, or has someone figured out a way to activate the solenoids without it? Truck is a 2004 4wd Excursion.

If one must use the dealer/specialty tool, I have a backup plan I figured I would try based on a TSB I read and some (hopefully) common sense. Without the tool, I would have to activate the ABS manually. According to a TSB, this can be accomplished by putting the truck up on a frame lift, put truck in 4wd, "drive" truck up to 40MPH and lightly apply brakes. The variation in speed between wheels should activate the system. Well, if I first purge the system of old fluid, I will still have some left in the ABS. So, I purge, do the ABS activation to swap out the fluid in that, and then purge again until only clean comes out. At that point I swap the caliper and soft line at one corner, being sure to block off the hard line with saran wrap and a zip tie so no excess air gets into a hard line. I then purge the air and do a final bleed on that corner. I then repeat with the remaining three corners. SHOULD give me a complete flush and proper bleed.

What does everyone think about this method? Or does someone have an alternative for what I'm trying to accomplish?
 

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Master BS'er
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I have never once had a problem with air getting stuck in the abs solenoids. I also don't use 2 people to bleed. I either use a pressure bleeder, or a mightyvac to suck it out through the caliper. Gravity bleeding works well too, but takes longer. Just stick the brake fluid bottle on top of the master reservoir and bleed it anyway ya want.

If you do get some stuck in there, just go make some abs stops in some dirt or something, then bleed it again. Highly doubt it'll be a problem though.
 

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Master BS'er
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And it's not a special tool, it's just a scanner that can activate the abs pump and valves. You can do the same thing by activating the abs when driving.
 

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Master BS'er
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I see, I should have read it closer. I thought you were replacing the master and abs unit.

You're not going to have a problem. No air is going to get into the abs unit unless you run the master cylinder dry. So don't do that. Prop the brake pedal down with something before you open the system. This will have the same effect as plugging a straw and taking it out of the water. The water stays in the straw, right? Same thing here. It'll keep all the fluid in the system.

Once finished, just flush all the fluid out until it's clear coming out of the calipers and you're done.
 

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He is trying to get all the fluid even the stuff in the ABS labyrinth cleaned out

i wouldn't worry about cycling anything I have the ability but have never even tried it ( flushed twice )


but to answer the question other than IDS or Auto Enginuity I don't know of a Hack
 

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Master BS'er
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Yeah I gathered, eventually. It's a good thing to do too. Can't tell ya how many times I've seen fresh brakes installed and the fluid is black.


Definitely don't worry about it. All fluid runs through the abs at all times, even under normal braking. I suppose there's a small pathway inside the unit from the dump valve back to the pump, if it even has a pump, that won't get flushed, but it's a non issue. It'll get clean fluid too once it's driven.
 

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don't play well w others
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I hate when people hijack threads, but this is along the same lines, so I apologize to the OP, and anyone else who may be insulted

Another shop sent me a truck they failed to fix. New calipers all the way around, bleed, etc.
They replaced abs sensors, rotors, and vss.
Told the owner it needed a master cyl. There are no codes, The 3rd brake bulb was out, so I replaced it.
I was skeptical, ended up replacing 2 bad rubber lines, and 2 rusted steel lines.

Eventually running a full gallon of brake fluid through the system, I replaced master cyl. Pedal still creeps to the floor holding brakes like at a stop light.

At this point, customer wants to replace abs pump and module with a known good unit.

Do I just power bleed the system after the module change just like when I put the master cyl in?

I have clear brake fluid coming out now.
 

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Master BS'er
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I hate when people hijack threads, but this is along the same lines, so I apologize to the OP, and anyone else who may be insulted

Another shop sent me a truck they failed to fix. New calipers all the way around, bleed, etc.
They replaced abs sensors, rotors, and vss.
Told the owner it needed a master cyl. There are no codes, The 3rd brake bulb was out, so I replaced it.
I was skeptical, ended up replacing 2 bad rubber lines, and 2 rusted steel lines.

Eventually running a full gallon of brake fluid through the system, I replaced master cyl. Pedal still creeps to the floor holding brakes like at a stop light.

At this point, customer wants to replace abs pump and module with a known good unit.

Do I just power bleed the system after the module change just like when I put the master cyl in?

I have clear brake fluid coming out now.
Key off, pump the brakes until the assist is gone and the pedal gets hard, does it still sink to the floor? If so, and you're convinced there are no leaks and it's not the master cylinder, then I suppose a dump valve could be just slightly stuck open, if that's the case, a few abs stops may un-stick it. I've yet to ever see this happen though.

But we're getting ahead of our selves.

And yes, you would bleed it exactly the same as you normally would. If air does get stuck, which it probably won't, activate the abs a few times while bleeding.
 

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don't play well w others
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I am sure no leaks. Went so far as to even replace the copper washers on line that is good, but I suspected a leak. I have been through it, and am confident I have all the leaks solved.
I think I will take it for some good windshield kissing trips tomorrow, then get back to you. Thanks for the help
 

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Took it for the shake down like you said.
First time nailing the brakes, it was like old school, rear end tried to pass the front, all 4 wheels locked up.

Second time, the ABS pump kind of farted, and shook the pedal.
I kept it up, each time, the brakes got better and better, it is acting like an ABS truck now, you hear the pump, and it hammers your foot. Truck stops straight as can be.

It still has a creep down pedal on sitting and holding the brake.

I am going to power bleed it again this week, and see what happens, but I have no way to do the 40 mph bleed like you said.
Any sugestions?
 

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Master BS'er
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You just activate the abs to move the bubbles that are stuck in there. Hopefully jar them around and then go back and bleed it again. The idea being that the bubbles won't be stuck anymore. Don't really need a scanner for it, abs stops while driving should do the same thing.

So if the pedal gets hard, but sinks, that's not air, it's bypassing, or leaking internally. The only places is can do that is the master cylinder, or possibly the abs unit.
 

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I replaced the master cylinder when I was doing the line repairs, so if this round of pressure bleeding dont firm up the pedal, I will replace the unit. I will get back to you with the results.
Thanks for the help.
 

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Project Shamu
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OBS's had a TSB for the booster being bad causing a Sinking pedal, mine has done it the last 5 or 6 years i've owned it. Just never got around to replacing it because it still stops great.
 

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i solved the "sinking pedal" on my 89 by putting the F-SuperDuty master cylinder on it.
it uses a 1 3/8 bore piston in the master instead of the 1 1/4 the 250 and 350 uses, and the 1 1/8 piston in the 150

i had enlarge the mounting hole in the booster by a few thousands, and oblong the holes in the mount on the master, but it worked much better than the smaller piston master.
 

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don't play well w others
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This isn't the master cylinder.
Another shop did a brake job on the truck, and left the brake hose off, while they waited on a caliper delivery ( finally got a straight answer this morning)
The master cylinder ran out of fluid, causing the ABS pump to suck air.

There are ports and valves in there that can't be bled in the conventional way.

Going to try another pressure bleed this morning, because I got the pump to start working Saturday, and have my fingers crossed all functions properly when that one is complete.
 

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oh, ok. that is why i do not let "techs" touch anything. if you do not call yourself a mechanic, you are nothing more than a parts changer.
 

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Sad thing, this guy swear by this mechanic.
" been going to this guy for 40 years"
 

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Master BS'er
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The techs are the most valuable asset in the shop. Often times the mechanics make more money for the shop, at least on paper anyway.

It gets complicated how that actually works out.
 
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