Another RABS problem
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Tuned
Joined: Jan 2004
Posts: 325
Likes: 1
From: B.C.Canada, EH?
Another RABS problem
1993 Aero 4.0L AWD. My RearABS light is on. I have checked all the connections under the hood and cant find a problem there. Out of desperation,I pushed the brake pedal as hard as I could with both feet, and started the van. The ABS light did not come on...until I released the presure,then it came on instantly. Can someone point me in the right direction of where to check next?
Thanks...this things really beginning to P***me off!
Thanks...this things really beginning to P***me off!
Thread Starter
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Tuned
Joined: Jan 2004
Posts: 325
Likes: 1
From: B.C.Canada, EH?
ken1mod....Shuttle valve?...Is that the same as the proportioning valve,directly under the master cyl? Is there a procedure for repositioning this valve?
Mormakil...I'll check that tomorrow. How is the sensor checked? Thanks
Mormakil...I'll check that tomorrow. How is the sensor checked? Thanks
Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
shuttle valve, proportioning valve, combination valve all same-same....Ford has used the names interchangeably
has a black plastic housing spst vertical pin switch in center top that becomes corroded and jams, senses position of proportioning valve piston and reports to RABS controller under radio
piston valve also becomes corroded...remove end cap and clean....careful...loaded with powerful spring and small rubber plug seal in end of end cap....if finish on piston is damaged-replace combination valve
rear axle sensor is a Hall effect magnetic pickup that works off a steel toothed wheel mounted on ring gear outer edge....can be checked with portable o scope but easier and cheaper to just replace....they do fail....also check for connector corrosion and damage to wiring
search Aero forum for RABS, lots of good write ups
RABS light on won't kill you, just puts the brake system into non rear ABS operation, like pre ABS....as long as rest of brake system is up to specs...i replace fluid every 2 years, saves lots of corrosion and RABS problems
has a black plastic housing spst vertical pin switch in center top that becomes corroded and jams, senses position of proportioning valve piston and reports to RABS controller under radio
piston valve also becomes corroded...remove end cap and clean....careful...loaded with powerful spring and small rubber plug seal in end of end cap....if finish on piston is damaged-replace combination valve
rear axle sensor is a Hall effect magnetic pickup that works off a steel toothed wheel mounted on ring gear outer edge....can be checked with portable o scope but easier and cheaper to just replace....they do fail....also check for connector corrosion and damage to wiring
search Aero forum for RABS, lots of good write ups
RABS light on won't kill you, just puts the brake system into non rear ABS operation, like pre ABS....as long as rest of brake system is up to specs...i replace fluid every 2 years, saves lots of corrosion and RABS problems
Last edited by 96_4wdr; Jun 3, 2006 at 01:55 AM.
Elder User
Joined: Aug 2005
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When my rabs light came on, I lost rabs. this is basically a rear wheel slip sensitive proportioning valve. without the computer, full pressure is sent to the rear.
I had severe rear wheel premature lockup and the vehicle was dangerous even in dry weather, in wet it was murderous.
RABS sucks even under best conditions. I installed an adjustable proportioning valve in rear hydraulic line and now enjoy the best brakes my 91 ever had.
I respectfully disagree, if rabs quits, you need to do something. My valve was 38.00 on ebay and I can turn up pressure when I tow.
Ken
I had severe rear wheel premature lockup and the vehicle was dangerous even in dry weather, in wet it was murderous.
RABS sucks even under best conditions. I installed an adjustable proportioning valve in rear hydraulic line and now enjoy the best brakes my 91 ever had.
I respectfully disagree, if rabs quits, you need to do something. My valve was 38.00 on ebay and I can turn up pressure when I tow.
Ken
Thread Starter
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Tuned
Joined: Jan 2004
Posts: 325
Likes: 1
From: B.C.Canada, EH?
96_4wdr and ken1mod....thanks so much for the info. I'm going to give it a try today and see if I can figure out where the problem is. I searched the RABS messages last night and some people mentioned the RABS valve unit may also be the problem. I will check that too.
Once again,thanks to all for the help!
Once again,thanks to all for the help!
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Junior User
Joined: Jan 2004
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How is the brake pedal? and how are the brakes? Is the brake light on as well? If the pedal is firm and the van stops good then it probably means that the RABS is non-operational and if you are careful in wet weather you'll be ok until you can sort it out. Also I understand there is a way to pull codes from the RABS similar to the engine computer.
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Elder User
Joined: Jan 2004
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From: North Alabama
Ken,
Is that as simple as removing the RABS valve and installing the one you mentioned? I never have liked these RABS and would like to have real brakes again.
Is that as simple as removing the RABS valve and installing the one you mentioned? I never have liked these RABS and would like to have real brakes again.
Originally Posted by ken1mod
When my rabs light came on, I lost rabs. this is basically a rear wheel slip sensitive proportioning valve. without the computer, full pressure is sent to the rear.
I had severe rear wheel premature lockup and the vehicle was dangerous even in dry weather, in wet it was murderous.
RABS sucks even under best conditions. I installed an adjustable proportioning valve in rear hydraulic line and now enjoy the best brakes my 91 ever had.
I respectfully disagree, if rabs quits, you need to do something. My valve was 38.00 on ebay and I can turn up pressure when I tow.
Ken
I had severe rear wheel premature lockup and the vehicle was dangerous even in dry weather, in wet it was murderous.
RABS sucks even under best conditions. I installed an adjustable proportioning valve in rear hydraulic line and now enjoy the best brakes my 91 ever had.
I respectfully disagree, if rabs quits, you need to do something. My valve was 38.00 on ebay and I can turn up pressure when I tow.
Ken
Tuned
Joined: Oct 2005
Posts: 271
Likes: 1
From: Chesapeake VA
I had a scary incedence today. Pulling up to a stop sign, wet pavement. When I pressed down on the brake, the LR tire started skidding. I pushed harder on the brakes and stopped. Didn't do it again. On wet pavement it scared me when I was stopping at a stop light. Full brake pressure, started skidding to the stop light, front wheels twisted to the left all the way. Stopped right at the line. Got new tires soon after. Happend one time after that. Recently I noticed brake fluid on the side of my proportioning valve. A little droplet where the nut it on the side.
Elder User
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You don't even have to remove the rabs valve, it fails full open. I tried to remove mine but it was hopelessly frozen to the lines. No problem, install adjustable proportioning valve at M/C plumb into line that goes to rabs valve. I got my (Wilmot, i think) valve off ebay for about 40 bucks. fully adjustable. great. good brakes. last part of job is to remove bulb in rabs light. full anti lock on my acura is WONDERFUL but rabs sucks.
ken
ken
Elder User
Joined: Jan 2004
Posts: 558
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From: North Alabama
Mine hasn't failed; in fact, it was new just 6 months ago. I miss the old no-frills brakes on my 65 VW van. Not even a power booster, but you could stand on the pedal and stop the van when you had to.
Originally Posted by ken1mod
You don't even have to remove the rabs valve, it fails full open. I tried to remove mine but it was hopelessly frozen to the lines. No problem, install adjustable proportioning valve at M/C plumb into line that goes to rabs valve. I got my (Wilmot, i think) valve off ebay for about 40 bucks. fully adjustable. great. good brakes. last part of job is to remove bulb in rabs light. full anti lock on my acura is WONDERFUL but rabs sucks.
ken
ken
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