[updated:LAST EDITED ON 16-Dec-02 AT 02:44 PM (EST)]I've got the same '93 (AWD) Aerostar it sounds like. I replaced the front pads last week, and wah-lah ... amber ABS warning light and red brake light. I've tried multiple things like a little pressure on the pedal while "breaking" the lines around the P-valve to possibly reseat an "unseated" needle in the valve, tapping the P-valve, etc. I can't bleed the lines because the bleeder screws are stuck good and fast, and I'm afraid I'll sheer them off if I put any more pressure on them.

I assume the problem is caused by pushing fluid backwards from the front cylinders when the new pads were installed (strange that this is my 3rd set of pads and this has never happened before). If I knew it was the p-valve, I'd simply replace it, but if I can't bleed the system afterwards, that probably would be a bad idea. If "gunk" got pushed back up into the master cylinder or p-valve, is there a way to bleed the garbage out without then getting much/any air in the system (since I can't bleed it)?

Thanks!

 

[updated:LAST EDITED ON 30-Dec-02 AT 04:32 PM (EST)] This blasted RABS is the Devil! I have been reading the forum for a year now trying to diagnose my 91XLT RABS, and still no luck. I replaced the master cylinder a year ago and have replaced the front and rear brakes, and bled the entire system over the last month. When I did them, I cleared all the fault codes from the OBDII and all my RABS/BRAKE lights went out. That lasted for a week. Now the RABS comes on about 2/3 of the time when the van is first started for about 5 minutes, then goes out. Brakes are still spongy and basically go to the floor, although the van seems to stop pretty well. This last weekend, I noticed while driving that the rear brakes seem clumsy--meaning that they were all of a sudden coming on very hard while braking moderately and shuddering the van. Today I went out to try and read the ABS code, and low and behold, no RABS light. So I went driving around the block and found that when I brake really hard, the rear brakes are sticking. I'm thinking it might be time to rebuild or replace the rear cylinders and the master cylinder again. Anyway, when I pull into the driveway and restart the van, now the RABS light comes on. I promptly go to read the code and no code is outputed by the light. It just continues to blare in my face. Any ideas on any of this? By the way, I have the rear brakes adjusted what I would say is correct because they engage pretty firmly with about half the travel of the emergency brake.

Thanks, Dave

 

Sorry, didn't mean OBDII, wrong vehicle.

 

mendeldl:
Try adjusting your rear brakes. These are prone to being out, despite having automatic rear adjusters. When the RABS is energized on start up, it does a self test sequence and briefly activates both solenoids on the RABS valve assembly. With rear shoes out of adjustment, the RABS test "sees" a low pressure event and thus the signal.

 

I really think the rear brakes are set correctly. In another post I put that I had set them so that when I engage the parking brake, they are on full at about half way through the travel of the lever. Seems about right to me.

Here's the link:
https://www.ford-trucks.com/dcforum/DCForumID94/917.html

Any help on this would be greatly appreciated.

 

 

Here is one for you who understand all this stuff... I bought 4 aerostars, one runs super great, the other 3 need work...
I purchased and towed the 1994 from Long Beach to Hesperia, Ca no problem, used my tow dolley...the battery was not connected... no incidents
It sat 6 months, I then put it onto the Dolley to tow it to 29 Palms... OH WOW!!
I had started it up to load it onto the Dolley, and left the battery connected when I went off towing it in the night / quiet / traffic free hours...
About 15 miles into this tow, my tow Aerostar "came under load / slowed down" more and more, something was going on back there at the towed vehicle....
I stopped, everything looked ok, I noticed nothing, no flat tires, so I again got rolling, at 2 AM...
about 5 miles later, at 55 mph, it began to drag again, big time, I pulled over, got out to looky look, the right rear tire on the towed vehicle was smoking, no emergency brake mistake, I was now very puzzled, thought that somehow the wheel bearing must be causing the problem...
I took the van off the tow dolley, drove it around, no problem at all, put it back on the dolley, 5 miles later, happened again... wow!\
I again took the van off the dolley, turned it around, put the back wheels onto the dolley, towed it backwards the next 55 miles, no problem..
As I went along puzzling this strange situation, suddenly it came to me, the only difference is, this time the battery was left hooked up, nothing at all was turned on, no lights, switches, etc.
The ABS system must have sensed something and locked up the right rear wheel on the towed vehicle...... I can think of no other reason...
I got into Landers, CA at 6 am and stopped for coffee, my pal there had had a very similar happening with a towed automobile, and called triple a to haul the vehicle, took it off the dolley, he never had figured out what happened..

Anyone else have this happen???? Thanks budstadler@yahoo.com

 

That sounds very strange. I guess you never tried towing again with the rear wheels on the ground and the battery disconnected?

It is unlikely to be the ABS, since that actually requires your application of the brakes to generate pressure on the pads, with or without ABS. Could some springs in the drum brake have come loose and allowed the shoes to come into contact with the drums?

 

If you can't get the rabs working, just install an adjustable proportioning valve in front of the non-functioning rabs control valve. I did this and now have excellent brakes.

Do fix this problem before you bend metal.

ken