Rear abs trouble

[maniac_3_2000]

Okay I spent a better part of a weekend trying to bleed my brakes. I was unable to bleed my rear brakes, because the ABS modulator or hydraulic unit (rockauto calls them both the same name), was stuck closed. Unfortunately the car was given to me with the front passenger side brake line detached from the caliper. I'm not sure how long its been that way, and i'm assuming alot of moisture got into the system. I started by bleeding the master cylinder, then I bleed the front brakes. After I couldn't bleed the rear brakes and discovered the abs modulator, I bleed the line that goes from the master cylinder to this unit, in hopes that the unit would re open.

As far as I can tell you can't directly bleed this unit. If its stuck closed because of air inside of it, what am I supposed to do?

My first thought is if i get a new unit, if it comes in an open position, before I plug it into the harness, try and bleed the rear brakes in hope that it gets the air out of the abs unit to begin with so that when I do connect the harness into it, it wont automatically shut on me. All this is just guessing. I am hoping someone has had to replace this unit, and knows how to bleed it and the rear brakes.

 

[FIND]

before you go too far, start your truck and try bleeding your rear brakes with the engine on. The extra pressure from the vacuum assist may get you going there. Might not actually be stuck, might just be clogged. The 92 I have right now was actually like that when I first bought it, it had sat for a year and a half and had a leaky wheel cylinder. I tried bleeding it and couldn't get anywhere at first. Eventually I did it with vacuum applied to the booster and was able to get enough pressure to get everything working normally. Also, be sure to take your bleeder screws all the way out and clean them thoroughly, can make a world of difference.

If you replace the unit, just bleed the brakes as normal. It will take a while, but you will get all the air out eventually.

 

[92exp4x4]

What year is your truck? I assume its the 01 sport mentioned in your description?

I think there is a special bleed procedure for the newer units but I'm not totally sure. You may have, but if not; try searching the other forums for your newer explorer.

 

[FIND]

lol, I didn't even read that part, I just assumed it was a 91-94. Even with newer trucks, I just bleed the brakes as normal. Takes a little bit, but eventually you get the air out of the modulator.

 

[maniac_3_2000]

No it's a 1991 ford Explorer. I actualy dont even own the 01 sport anymore. I got a newer car. I am fixing a 91 explorer for a family member. I replaced the rear abs hydraulic unit. I can now get fluid to the rear using the hand vaccum pump. But even though I got clear clean fluid all the way to the rear, the brakes still weren't working. I had a buddy sit in the car and do the old style peddle pumping break bleeding, and each time I opened it, I only got a really really slow drip.

I am assuming it might be the master cylinder, but When I bench bled it, both the front and rear ports moved the fluid evenly and I had no trouble at all with it. And the front brakes can bleed pedal style real easily without a problem.

As a side note I have left the abs unit unplugged from the harness, cause someone told me that I should make sure everything is bled and working first before I let power run to it, or the computer might shut the valves on me, I dont know if this is true, or if by not connecting the harness its actually giving me trouble in properly bleeding the rear.