Solved Still NO brakes!

[410Fortune]

Yes 95 is an odd ball year
Do you have a 4 wheel ABS pump? Not just RABS right?

I deleted my RABS valve a long time ago I got tired of having air stuck in there......
The 4wabs pump needs to be powered by a scanner before the air will release
The RABS valve has a bleeder on it

I have had good success bleeding the stuck air from the 4wabs systems by driving it, find some gravel and get the ABS brakes to activate....the air will move downstream where it can be bled

 

[gmanpaint]

95 has the 2nd gen HCU pump ABS system. Being it is a 60 pin PCM, and it doesn't except the OBD2 connector........

Ford Must have made some way to hook it up to activate it for a bleed. I'm wondering if the OBD2 dummy port under the dash actually works for the HCU?

 

[Spudhut]

I find this thread very interesting. Im eager to see what the outcome will be. High five for the effort!

@gmanpaint - what did you do to delete ABS system? Did you cut it out entirely and re-plumb the tubing?

 

[gmanpaint]

I find this thread very interesting. Im eager to see what the outcome will be. High five for the effort!

@gmanpaint - what did you do to delete ABS system? Did you cut it out entirely and re-plumb the tubing?

Correct. Removed the HCU, added a brass T for the front lines and a new line to the MC, then a Prop valve/short line, for the rear line. Had to cut off the stock fittings, re-flare the lines with a standard nut fitting. Front & rear stock line fittings to the MC are different. One is metric, one is SAE. Crazy.

A friend looked at AllData for the 95's bleeding procedure earlier today. It is saying to bleed the HCU a certain way, with a 40 pin adapter, and the actual manual bleed procedure is not normal. News to me, and he is reading the procedure to understand it better, and will get back to me with his findings on this system.

I too am interested in this 95 bleeding, as it has perplexed me for years. I will share what he says, when he does.

I actually had this posted in the 95's registry years ago, and just found it. It tells how to bleed the 95's ABS pump (HCU). I never tried this tho. lol


Perform conventional brake system bleed.
Prepare an appropriate method of connecting individual circuits and wires to ground. This connection must be sound, with very low impedance to the battery negative terminal (can use some stainless hat pins and alligator clips on test leads).
Turn the ignition switch to the ON position.
While an assistant presses down on the brake pedal:
*a. ground circuit 599 [PK/LG], pin 19. (4WABS Relay #1)
b. ground circuit 510 [T/R], pin 27. (Rear Dump)
c. ground circuit 498 [PK], pin 15. (Right Front Dump)
d. ground circuit 496 [O], pin 26. (Left Front Dump)
The pedal will fall to the floor.
Disconnect the ground connections made in parts 4b, 4c, and 4d. *Leave the connection made in part 4a. Allow the brake pedal to return.
Repeat steps 4 and 5 once more.
Ground Circuit 539 [PK/LB], pin 29 for one minute. The ABS pump motor should run for the entire minute.
Perform conventional brake system bleed.

 

[Spudhut]

@gmanpaint - Well done on the info Sir!

I'm debating on removing my ABS from my SAS 97', new lines/brass blocks are not an issue - "Cake walk in the park". I finally got my rebuilt calipers back on the vehicle this weekend and will need to start bleeding.

Any Idea on required pressures needed for rear (proportioning valve type)?

 

[donalds]

^^ yeeyeee

 

[gmanpaint]

@gmanpaint -
Any Idea on required pressures needed for rear (proportioning valve type)?

When I first installed an adjustable valve, I thought setting it at 600 psi would give me the proper Bias, but over time, I learned that is too high. It caused the Master to bypass on hard braking, and the pedal hits the floor. I run it around 400 psi now. With an adjustable valve with a dial, you can just adjust it accordingly to your application. It doesn't hurt the system, to adjust it when wanted/needed.

Your 97's HCU has a key electrical component, that needs retained doing the delete. There are some threads here on that subject if you can find them. The 95 does not need to do this.

Keep the metric fitting on the stock line at the master and re-use it. It's a PITA to find alone.
M12x1.0x3/16" line.

 

[IronCurtain]

I actually had this posted in the 95's registry years ago, and just found it. It tells how to bleed the 95's ABS pump (HCU). I never tried this tho. lol


Perform conventional brake system bleed.
Prepare an appropriate method of connecting individual circuits and wires to ground. This connection must be sound, with very low impedance to the battery negative terminal (can use some stainless hat pins and alligator clips on test leads).
Turn the ignition switch to the ON position.
While an assistant presses down on the brake pedal:
*a. ground circuit 599 [PK/LG], pin 19. (4WABS Relay #1)
b. ground circuit 510 [T/R], pin 27. (Rear Dump)
c. ground circuit 498 [PK], pin 15. (Right Front Dump)
d. ground circuit 496 [O], pin 26. (Left Front Dump)
The pedal will fall to the floor.
Disconnect the ground connections made in parts 4b, 4c, and 4d. *Leave the connection made in part 4a. Allow the brake pedal to return.
Repeat steps 4 and 5 once more.
Ground Circuit 539 [PK/LB], pin 29 for one minute. The ABS pump motor should run for the entire minute.
Perform conventional brake system bleed.

THANK YOU!

Guess who's gonna be trying this tomorrow!?!?

I just need it dumbed down a bit....

Where exactly do I find those wires...going in the HCU? Where are the pins...? And I basically just ground them to the negative terminal as described?

 

[gmanpaint]

I believe at the harness going to the HCU. I haven't tried that procedure, since I just deleted the ABS. I will ask my friend later tonight to verify the pin source.

 

[IronCurtain]

No worries at all.... I'll do it if I can find the right pins, if it works awesome if not no worries back to the drawing board. Pics of the wiring harness(s) going to the hcu:

You can see the one with 3 wires... And then there's one with I think 4 all blue wires.. Which is weird.

 

[IronCurtain]

This IS the hcu amirite? :

 

[gmanpaint]

Yeppers, that's the trouble maker! lol

 

[CDW6212R]

There should be an unused connector along the fender near the ABS/HCU. That's where I'd suspect all diagnostics and HCU bleeding is done through.

 

[IronCurtain]

The one where I get codes from? I use a small wire to jump from pin to pin, then from another pin to battery, turn key to on and CEL flashes according to tripped codes.

Anyway, here's a recap of everything so far :

(Rusted) brake line developed hole 6 inches from the brake hose near right rear wheel. Brake pedal traveled almost to floor, but the front brakes were enough to stop vehicle relatively ok. Drove vehicle like this for a couple weeks, until one day I get off highway and pedal travels pretty much to floor, car takes extra distance to stop. Drive another mile or so, and brakes fail completely. I fill the MC, but no new leaks.... only leak is where the hole is near rr wheel. Not sure if MC was completely empty at time of loss of all brakes.

I replaced both rear brake hose, and brake line from MC to LR hose, and from LR hose along rear axl to RR hose. Still zero braking ability and pedal travels to floor easily. Couldn't bleed properly because bleed screws on rear calipers were basically rusted off.

Replaced both front calipers and pads. Bled both front calipers....still no braking ability and pedal travels to floor easily.

Replace rear calipers and bleed all 4 calipers...very very small SMALL braking ability but pedal still travels to floor easily.

It snows 3 inches so I take the Explorer to big parking lot, get going well and slam on brake pedal, and hear and feel the abs system activating. I did this at least 7 times.

Replace MC after bench bleeding it, bleed all 4 calipers (RR, LR, RF, LF)..still zero braking ability and pedal travels to floor easily, BUT will pump up after 5 or 6 pumps and will stop vehicle relatively well once pumped, but then right back to traveling to floor once foot is off pedal for a few moments. Not exactly sure if this is new because I had my gf helping me bleed until I replaced rear calipers and MC, then I had a friend help and he's the one that noticed they'd get pressure after 5 or 6 pumps.

Plug both outlets coming out from MC, brake pedal is hard as a rock and I can't push it down.

Take apart old MC, don't notice and visible signs of undue wear and tear on seals, pistons, or (bore?)... Put back together, bleed, and replace the new MC with the old one. Pedal travels easily to floor BUT it takes only 2 or 3 pumps to get pressure and VERY GOOD braking ability. Like really good. But once I let off brake pedal for a few moments, it's back to traveling to floor and needing to pump up a couple times to get pressure and stop vehicle well.

-There are ZERO leaks from the system.
-When the pedal is depressed a couple of times, fluid level in MC goes down, then back up once pedal is released.
-Brake hoses do not balloon.
-I've bled all 4 calipers multiple times...again and again and again. And again.
-If brake pedal is pumped 2-4 maybe 5 times pressure builds and vehicle stops on a dime.
-once pedal is released, and pressed again it goes to floor easily and needs to be pumped for pressure and proper braking ability.
-There is SOME (very little) braking ability when pedal is pressed to floor on first press, but not much at all.
-I'm at my wits end and am willing to try just about anything. Will not give up tho.
-Extremely grateful for everyone's input and suggestions...and patience!!

 

[gmanpaint]

OK, so I have some info, but your going to have to decipher some of this yourself.

The 40 pin connector is located under the Aux relay box #1 at the front Dr side fender as shown in the diagram below.

The connector and the pin outs:

So after disconnecting this, find the pins, and do the ground method as previously posted.

The circuit diagrams to follow at your own risk

Anybody want to help with this, by all means speak out!

 

[410Fortune]

Man I hate friggin ABS brakes on these trucks

 

[Mbrooks420]

I’ve always loved my ABS. It functions great, and I’ve never had a single issue with them.

 

[IronCurtain]

Lol well isn't that good for you.

I'm sure what he's saying is "I hate when there's a problem with the abs because they're such a pain in the ass to work on"

 

[Mbrooks420]

A lot of people hate ABS, period.

 

[boominXplorer]

Can you take pictures of each caliper (or at least the front) including bleeder screw? I feel that if you still don't have a pedal you very well could have a miss installed caliper.