ABS question

[92exp4x4]

How fast are you going in the yard? There is a minimum vehicle speed that needs to be met before the system will "arm". I think it is around 5-10 MPH. Once you are over that minimum speed, it will not matter the surface you are on.

Also the fronts do 70% of braking and Ford designed this system to operate the front and rears seperatly or at the same time if needed. Your fronts will lock up before the rears because they are so much more powerful. It is very possible for the system to kick in the fronts and not the rear at the same time. Remember the module is looking at the fronts as two wheels and the rear as the diff only.

If you can activate the system at all then chances are its working fine. I really think your truck is working as it should. My later Exs do exactly what you describe.

 

[AndyM]

okay chaps i have the offending item in my hand. The module that controls the red and yellow warning lights and the RABS system.
I have a load of photos but i cant post them. I don't know why, i will ask the moderator.

Anyway, the module lays below the heater control panel. You access it by removing the ashtray, NOT the radio. It sits right beside the ashtray compartment and is attached to the front-bottom of fascia, close to your right leg. It is held in a bracket with the control module that makes the beeping noise when you open the door. It is a smaller Grey/Black box, about the size of a *** packet. The RABS module is metal and gold colored and is about 4 inches long by 2 1/2 inches.

hope this helps someone, because now i have no RABS warning light...yahoooooo.

 

[Currency]

Yeah whenever my fronts lock it I am driving under five mph for sure. I try not to tear my dads yard up as the 700 raptor does that for him and the tractor hauling logs and cars around every other week.

We got an inch or so of snow the other night and without my 4wd working because of the shift motor (I did rebuild it twice to no effect) I was a little worried I wouldn't be able to go anywhere. Well the last owner had regular street tires on it and I have the good year wranglers which may have helped a little. My front's locked up a few times when I was braking but I did managed to get stopped each time they locked up.

Also with the 3.27 L/S rear end it only went sideways when I made it if it helps anyone. Another thread on here suggested that with a L/S the rear end may come around on you unexpectedly which was not a problem for me. We got around an inch from what I seen plus some ice under that.

 

[92exp4x4]

My bronco has a L/S rear and Ithink it does try to meet its front more than others. I guess its because both tires break loose at the same time. I'm not sure its just a guess.

I would say your ABS is working as it was designed, now if it works in the real world thats another question!

 

[Currency]

Yeah I would say it works fine, it doesn't bother me sliding on a road as much as it does sliding while off roading. At least my insurance covers me hitting a car compared to a tree. but then again I may have a deductible of around $500

As for the limited slip diff, I've been able to drive out of places that an open diff shouldn't attempt driving in. Foot deep off road tracks will end the fun if you have an open diff and I can power lock it in the tracks forward or reverse and still just drive out of it. Then again I'm not the easiest on vehicles when it comes to playing around. I just figure if I tear it up I can always fix it better then it was before I tore it up :

 

[RedneckRambo]

i wish i had a l/s diff the day i high center my rear axle. had tracton on the side that wasnt spinning

 

[khansen46]

AndyM - thanks for the tip on the location of the control module. I'll look it up if I have further problems.
I went to the salvage yard today and picked up a used RABS HCU today, since my inspection is coming up again soon and I'm still not willing to fork out the money for a new one. Once installed, I no longer have the brake or ABS lights lit up. However, I have absolutely no brake fluid getting to the rear brakes. I put in speed bleeders, but nothing was coming through. I also tried a hand pump at the bleeders - nothing. Being completely fed up, I picked up a double female connector from Auto Zone and bypassed the HCU altogether. I plugged both ports in the HCU and left it plugged in. The lights have stayed off, and the brakes work better than they ever have since I've owned it. Considering my 91 has 237,x.. miles, I think this will be a permanent fix. I've spent 2 years fighting this issue, and I'm done with it.
Next project: leaky seals in steering box...