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ABS bleed procedure?

N

nwcherokee

NAXJA Forum User
Location
Bremerton, WA
I have replaced the stock rubbers to long S/S lines. Now that I've bled the system, i'm not getting anymore bubbles & the brake pedal is firm, so I think i'm good there, but when I turn the ignition to "ON", the ABS booster pump just keeps running. I've read the manual which says to crack the lines at the Master to bleed out, which I haven't done. I had to replace the end of 2 hardlines due to stuck flare nuts on the rear & front passenger, so by now I'm tired of dealing with the brakes. Can I just pull the ABS Relay & do without or is the ABS necessary for proper functioning of the system?
I'm not fully understanding the bleeding procedure for the ABS Modulator either? Do I crack the lines until no bubbles, or until fluid comes out or what? Do I do that at the master cylinder or the modulator? Also, one of my double inverted flare unions didn't seat right & now it's leaking. Is there any way to get the brake fluid to stop pouring out the lines so that I can re-flare it without getting fluid everywhere? If so, what's the trick?

Thanks.
 
The proper method actually involves using a Chrysler DRB II (or III, I forget) machine to tell the ABS pump to run for the right amount of time while cycling the solenoids (inside the ABS valve body) in the right order to fully bleed the ABS module as well. I'm not certain that it can be done without the DRB tool. When I looked into buying one used, they cost at least four digits :shocked:
 
Oh yea that just figures! :smsoap:

Kastein, I read one of your post about swapping out a master & having a similar problem. I think I might just take it somewhere & have a shop do it. I guess the question now is, can I pull the relay & drive it to a shop or get my Dad's flatbed & tow it?
 
What year is it? If it's a 92 or later you can pull the relays/fuses, bleed it again, and drive it, but 91-down should be towed. Frankly, 91-down you should gut the ABS system and replace with a non ABS setup and forget about it, actually.

You could also do this with a 92 or later if you don't like ABS anyways.

Don't know what a dealer will charge, but bringing it to them would probably be best, or simply make sure whatever shop you bring it to has a DRB machine. Some hole-in-the-wall/shady shops may not have one and will just do the same thing you did.
 
Oh boy, it just seems to be getting worse:smsoap: Mines a '91.... go figure! I hate taking things to the dealer. I don't even take my DD Toyota Tacoma to the dealer for things. I have a local shop i've used before. I'll check them out first. I also have 2 4x4 shops locally, 1 of which I would take it to. I've got a big wheelin trip scheduled in 2 weeks. I've gotta get this fixed.
I would like to gut the ABS, mostly because that air compressor of a booster pump under the hood is freaking annoying. Every 3rd depress of the brake & it fires up. :hang:

Thanks for the help Kastein :thumbup:
 
yeah, unfortunately it does - along with the pedal assembly, I believe. Not entirely sure.

I know for a fact you can do the whole job using the master/booster and pedal assembly from a 95 or 96 XJ. Rip all the old crap out, install new booster and pedal, connect brake lines to prop valve on new booster/master, bleed it all, and you are done. Remove the ABS sensors and wires if you feel like it.

You can also use a WJ booster/master but I'm not sure how the pedal assembly compares/connects up to that.

This all gets even more complicated if you have a standard due to the clutch pedal.

Anyone know for sure if you need a different pedal assembly to put a new booster/master setup into a Bendix ABS equipped '91? Slightly different from a '90 or earlier but otherwise the same.
 
Well, luckily it's an Auto. Given my time constraints, I think i'll call a shop to see what they charge to bleed out the ABS. If it's gonna cost the same as a system swap I might go that route.
 
I'm honestly not sure the DRB tool can deal with Bendix ABS, when I wrote about the DRB tool I was thinking of the Chrysler ABS setup. Anyone know for sure?

With labor I would bet you can pick up junkyard parts to dump the ABS for less than getting it bled at a shop. I paid 65 dollars for my 95/96 prop valve, master cylinder, booster, and pedal assembly with brake light switch at my local yard. Ended up getting a WJ setup (since it was almost bolt-in for my non-ABS 91 MJ, I just wanted the dual diaphragm upgrade) and selling the 95/96 setup but I know it will work.

It will take around 45 minutes to pull the whole assembly at the junkyard if you're decent with mechanical stuff, and about the same to install it. Count on needing a pair of channel locks or a BFH to "adjust" a pinch seam or two on the firewall so that the bigger dual diaphragm booster will seat properly.

Oh, and enjoy the dual diaphragm booster... you should notice a big increase in brake effectiveness if you do this swap.
 
Well when you put it that way it sounds simple :rolleyes:
When you say 45 minutes, was it really 45 minutes? My 30 minute projects usually turn into a whole weekend & I consider myself pretty skilled in automotive projects. This whole process has been a nightmare!
 
It probably took me less than that to get it out of the donor vehicle. The worst part was the nuts holding the pedal assembly and booster to the firewall, getting to the top two was interesting due to space constraints under the dashboard. The hardest part of the install was the same two bolts. If you can double flare brake lines and bleed master cylinders, you will do fine, if you have never done those tasks you will end up learning how but it's not too bad. Budget a whole weekend if you haven't done it before, and make sure you have another vehicle running first so you can get to the parts store if needed.
 
Ha.... yea um, my XJ is our 4th running vehicle. I just learned how to do the double flaring 2 days ago, but i've never bled master cylinders. Can't be that hard, of course I thought changing brake lines & bleeding wouldn't be hard either :doh: Honestly the hardest part is gonna be finding a donor. I'm not finding any WJ's & all the mid-90's XJ's all seem to be manual tranny's.
The dealer is running a special $89 brake system flush. I'm wondering if that will include bleeding out the system. If so, i'm hauling it down there tomorrow!
I really appreciate all the info you are giving me Kastein. Much friendly over here when compared to TTORA forum(toyota territory off-roaders assoc.) My DD is a Tacoma D-cab.
 
Damn that kinda sucks.

No problem on the help... information wants to be free!
 
So does anyone know if the brake system will work normal with the ABS relay pulled? I have a friend who went to auto mechanic school & he said he pulled his ABS relay on his ride without any consequenses, other than the fact that he no longer has ABS.
 
Yours won't. Pulling the relays and fuses on a Bendix system means playing russian roulette with your brakes... there is no normal booster in that setup, without the pump working you could run out of pressure in the reservoir (that spherical or cylindrical metal thing next to the master cylinder, iirc) at any moment in time. At least, if I understand the way the system works correctly...
 
Do you think a full system power flush would resolve the problem? The guy at the garage that i've taken it to before says that if he recalls correctly, the accumulator should bleed itself & build pressure.
 
nwcherokee said:
Do you think a full system power flush would resolve the problem? The guy at the garage that i've taken it to before says that if he recalls correctly, the accumulator should bleed itself & build pressure.
Click to expand...

Don't know if that will do it or not.

The 90 FSM gives SQUAT info for bleeding the ABS system other than the standard RR/LR/RF/LF stuff. No info on using the DRB (early version) to bleed the pump/accumulator.

Note that the FSM does list the operating pressures at 1600+ PSI--and that to kill the pressure you have to pump the pedal, engine off, 40-50 times. Explains why most NFL kickers are former Jeep techs. :laugh:
 
joe_peters said:
Don't know if that will do it or not.

The 90 FSM gives SQUAT info for bleeding the ABS system other than the standard RR/LR/RF/LF stuff. No info on using the DRB (early version) to bleed the pump/accumulator.

Note that the FSM does list the operating pressures at 1600+ PSI--and that to kill the pressure you have to pump the pedal, engine off, 40-50 times. Explains why most NFL kickers are former Jeep techs. :laugh:
Click to expand...

I just read an internet article that stated the bleeding sequence is RR, LF, RF, LR??? It also stated that the system MUST be releived of ALL pressure completely before opening the system. Wish I had know that before I started! Also stated that the procedure for relieving the pressure is to pump the pedal 45 times while the ignition is off. :eek:
The entire system MUST be bled after any repairs, including the accumulators, pump, master cylinder and brake lines :doh:
 
First: As stated, pulling the fuse eliminates the power braking supplied by the electric pump. If the relay failed, and the hydraulics were intact, you could build minimal pressure for braking. I advise against that practice.

Second: Removing the Bendix 9 ABS, and changing over to the dual diaphram booster is painful, but worth every cramp, every scrape, every foul word. Wading through the threads is more painful:

http://www.naxja.org/forum/showthread.php?t=903934

http://www.naxja.org/forum/showthread.php?t=903927&highlight=ISO+flaring+tool

FWIW, when I converted my '90 with 4.0 and AW4, aside from installing a union for the rear line, and swapping over the front lines, all I had to do was drill the rod eye bigger and grind a flat spot for the 1990 brake light switch.

Third: Change the rear wheel cylinders to the '95/'96 size. The ABS cylinders are sized differently and won't work the same.
 
nwcherokee said:
I just read an internet article that stated the bleeding sequence is RR, LF, RF, LR??? It also stated that the system MUST be releived of ALL pressure completely before opening the system. Wish I had know that before I started! Also stated that the procedure for relieving the pressure is to pump the pedal 45 times while the ignition is off. :eek:
The entire system MUST be bled after any repairs, including the accumulators, pump, master cylinder and brake lines :doh:
Click to expand...

Careful of information you get over the internet!

FSM 90, 5-77 to 78, RR, LR, RF, LF.

Always start the farthest from the master cylinder and work back to the closest. RHD would be different, of course.
 
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