Hi,

New here hope posting in correct spot. Did a search but did not find answer.

So here we go:
1994 Ranger
2.3
5 Speed
Standard Cab
247,000 miles
One owner.

Issue, rear brakes lockup under moderate to heavy braking.
Details:
25 years never an issue one owner ranger.
Front brakes good.
Rear brakes good with new wheel cylinders.
Verified proper adjustment at a shop.
No trouble lights.
Innova® EQUUS 3145 Ford Code Reader shows no codes.
Rear brakes quit locking up when rabs is disabled pulling fuse.
Only pulled fuse for testing since brake lights and more are also disabled.
Visited local dealer to chat with tech forman. Dealers nolonger have a scantool for EEE IV systems.

So now hopeing someone has seen this combination of symptoms in the past. At this point I can only guess by starting a parts replacement strategy in the following order but hate to spend hard earned money at a guessing game that may not pay off.

First wheel speed sensor (least expensive).
Second abs control module.
Third abs hydraulic unit (most expensive and messy)

So what do you think about this plan of action and does anyone know if I should just skip some of the parts that won't do anything to help?

Thanks

 

Welcome to FTE.

I see you don't have any replies yet so I'll see if I can get things started.

You can query the ABS controller for trouble codes on your OBD-1 ABS system without a scan tool, by using a 12 volt test light to have the controller blink any stored codes by following the instructions member Rockledge posted, that are in the "Tech Info" thread. It's located atop this forums thread index page. Click on & open the Tech Info thread, scroll down to the "Brake & Suspension" header & click on how to pull 1994 ABS codes, then scroll down to post #4, use the procedure & let us know what you find.

If no ABS codes, seeing as how the rear wheel cylinders have been replaced, did the old wheel cylinders leak & get brake fluid on the brake linings??? Doesn't take much to cause them to act out & lock up. If brake fluid got on the shoes from the old cylinders leaking, or during installation of the new ones, replace the shoes, As cleaning the linings doesn't often work, or if it works, not for long before heat causes more fluid to migrate back to the surface & they lock up, or grab unevenly again. With slick winter roads coming, that could cause a spin-out, or accident. If contaminated Replace shoes on Both sides.

Some beginning thoughts for consideration, let us know what you find.

 

Thanks for reply have one question.

If the pads were the issue would they not also grab under heavy braking even when abs is disabled. No issues or lockups under that situation.

Edited to add this:
When this happens the brake peddle gets so stiff and the brakes do not release until the key is turrned off which seems to reset something electronic.

 

The additional Edit info is likely a clue, but right now, with so many unknowns surrounding the two events, I'm not sure it would be meaningful for me to speculate. I'd suggest looking for RABS trouble code clues & post All code Numbers, as they can help focus a trouble shoot.

Did the rear brake linings get a dose of brake fluid leaked, or spilled on them?

When whatever happened that caused you to replace the rear wheel cylinders, did all the brake fluid leave the rear wheel system While the brakes were being used?
If so & the ABS system was in operation, air could have gotten into the ABS valving & is causing mischief, in which case you'd want to apply a vacuum to the system while actuating the RABS valving to purge the air out & get new fluid in. If that's what happened, it might be best to take this puppy to a well known & trusted brake specialty shop & have them vacuum bleed the system.

 

I will see if can get the codes tomorrow or Saturday.

Just a heads up the shop that put in the cylinders (I don't .like doing drum brakes) said the cylinders were starting to seep. I went there because the lockup was happening before and still after cylinders and new rear hose.

I will call and ask on the pads and also pull codes for my next post.

 

Ok good feedback on the brake grabbing problem existing Before the shop wheel cylinder replacement!!!
I take it from your last post you don't know if they replaced the rear brake shoes, or if the old wheel cylinders had dripped brake fluid onto the old linings, or if the old linings were replaced & if they were replaced, did the new linings get fluid on them too????

SO, when you took it in for service, was it for the grabbing problem? If so, did the grabbing problem come about suddenly after some event?
Did the the brake master cylinder reservoir fluid level get so low that the dash low fluid warning light turned on?? If so, air could have gotten into the rear RABS valving during one of its locking/unlocking/grabbing fits during braking???? If the system was low, it could have drawn air into the RABS valving during one of its fits & that's causing mischief.

If the garage didn't know the fluid had gotten low & just did a normal brake bleed after the rear wheel cylinder replacement, it won't purge the air from the RABS valving, as that valving isn't activated during a normal brake bleed procedure. SO, if you think the fluid got low & sucked air into the RABS valving, inform the shop & see if they think its necessary & they have a scan tool that can activate the RABS valving & the vacuum system to pull a vacuum on the rear brakes while performing a RABS valving activation & vacuum bleed procedure & let us know how it goes.

Will be interesting to see if you find any stored ABS trouble codes.

 

Ok to answer some questions first.

The brakes seemed to start grabbing suddenly. But who knows as this happened during dry season not much rain so it could have been coming on slowly.
It was taken to the shop for the grabbing issue as there were no other known issues with the brakes.
There was no contamination on the shoes. The wheel cylinders were not leaking, they were just starting to seep with a bit of moisture on the end caps.
The brake fluid was low but not below minimum. The only time the fluid light came on was during braking when the fluid shifted during braking.
Lastly as a reminder. No lockups when abs fuse is pulled.
Only code in system I understand is an all clear code. 16.

Please let me know if any more info is needed. Also the link in the post goes to a non-existent page. I found a YouTube vid to pull the codes.

Thanks

 

Ok good feedback on how the trouble began & what the shop found on the wheel cylinders.

You likely didn't click on the how to pull abs codes on 94 link, I think its the 3rd/last one in the stack, here is the link to Rockledge's post in that thread with pictorials https://www.ford-trucks.com/forums/1...tml#post914253

Anyway, If you scanned & got an all clear & the brakes are still grabbing with the ABS plugged in, have a look at the RABS speed sensor, wiring to it & its electrical pins/socket connections for corrosion, bent pins, spread sockets, mashed, pinched, skinned, cut wire insulation to the speed sensor, or other corruption that might cause it to act out & be intermittent & cause the ABS system to think the rear wheels are locking up & have it pulse the rear brakes. EDIT: The RABS speed sensor resistance should be in the range of 1,400 ohms & not jump around when the wires are wiggled.
When it acts out, does the speed-o act up too, or if you have auto tranny does the shifting act out, or if you have cruise control does it drop out, or not take a set, as those systems also use the ABS rear speed sensor output signal to operate, so if the sensor signal is corrupt, they too can act out & those would also be clues to put the RABS speed sensor on the suspect list.
When the ABS system is disabled, we revert to normal/non ABS braking, so it isn't like the rear brakes aren't working, they just don't have the ABS function.
More thoughts for pondering, keep us posted on your trouble shoot.

 

Was coming back to edit to add this which I forgot earlier.

Rare if any pedal pulse. The rears simply lock. The additional info is when this happens the brake pedel returns to idle position but the brakes stay engaged, pedal can not be pressed more than a fraction of an inch. Must turn off ignition and restart to restore pedal and brakes. The severity of the lockup varies. Light taps on wet pavement lock the wheels but I can resume. It is hard stops on dry pavement that require power down and restart.

Have not noticed any speedo issues, also no cruise control or automatic transmission. Does have AC.

Edit. Side note. I did find the correct post with the embedded image for 4 wheel abs and a seperate link in the post to rabs. It was the link within the post that did not work.

 

Ok, well then I suppose if no ABS codes found & everything else mentioned checks out, that sorta leaves you looking at the under dash RABS controller to add to the suspect list???

 

Well it is dark and not sure if the shop is clear at work where I can lift the truck but I will check. If so I will check ohms. Have never pulled one of these sensors. Any specific wires to check?

Lastly I was hoping the stiff pedal would be a good clue.

If I have to chase down the issue with parts which order is best? My thoughts were.
1st speed sensor.
2nd under dash controller
3rd valve.

If the shop is not clogged I can test ohms tonight and return results.

 

No need to raise the vehicle to test the speed sensor resistance, as this model has an under dash ABS electrical connector on the drivers side firewall where the wiring harness feeds through the firewall, so you can open up & check across its pins to measure the sensor there.
The stiff pedal is a clue, but I'm not familiar enough with this braking system to make a good guess, other than the RABS controller seems to be acting out & you say the problem came about suddenly, but so far haven't been able to find any other clues to look elsewhere, so right now it seems your left with looking at the RABS controller, unless you've missed something feeding it corrupt signals & that's why I mentioned the rear abs speed sensor & wiggling its wires.

 

Okay then. I still have the single pin wire disconnected that I pulled codes with. Where would the connecter be to rest resistance? I saw a video about a round plug with 2 pins that is under the hood.

Thanks

 

I've seen that video too. Go here & enter the vehicle info to view the test connector wire color code.BBB Industries- Premium Alternators, Starters, Power Steering Products | TSB's & Wiring Diagrams

 

As soon as I turn in my expense report I will see if I can test. Shouldn't be too long.