rebuilding the ABS sensor, yay or nay?

Darth_Elvis

Darth_Elvis

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I have a 91 Mark VII and the dealer told me that I need to replace the ABS Sensor but they cannot find one anywhere. I was told that it can be rebuilt, is this a good idea and how reliable is the thing after being rebuilt for those of you who have done so:confused: Thanks
 
Darth_Elvis said:
I have a 91 Mark VII and the dealer told me that I need to replace the ABS Sensor but they cannot find one anywhere. I was told that it can be rebuilt, is this a good idea and how reliable is the thing after being rebuilt for those of you who have done so:confused: Thanks
Click to expand...

Don't know exactly how one could be rebuilt. But they can be replaced.
Ford Parts Direct on Line claims to have the ABS sensors for our cars. :)

Good luck
 
No I don't drive in the snow... And I did go to forddirect.com and ordered the ABS Sensor (hurrah hurrah!) but then got an e-mail saying that it was no longer available, d'oh! So I'm back to square 1
 
There is no way to rebuild an ABS sensor. Are you sure they weren't talking about the ABS pump motor? That's the only thing in the ABS system I could imagine them rebuilding, and also the only one I could see it being a problem getting. What are your symptoms that you brought it to the dealer for in the first place?
 
The only symptom I have is the light. I suppose I could just cover the light with a sticker, but I would prefer to fix the thing. I've been told a coup;e times now that a sensor can't be found, so do I just let it be?
 
I've been involved with more than a few posts about the brake system. I got my car for free because Lincoln wanted $3,500 to fix the brakes. They couldn't find the problem, were honest about it, and wanted to install ALL new components.. in order to warranty the work i suppose...

So, I was forced to learn about it. It turned out that the problem was a clogged filter hidden inside and at the bottom of the fluid reservoir... fixed for $6 for a junkyard reservoir replacement..

imo, you might want to get a 2nd opinion from another shop or mechanic.

--------------
Anyway, how about you tell us exactly when the "Check anti-lock brakes" lamp goes on, and when or if it EVER goes off.
Is it ON as soon as you turn the key and does it stay on forever?

Also, are there ANY other symptoms.. Do you ever lose some or all braking power?
Is the pedal hard or mushy? Does pedal resistance ever change? Are there any brake fluid leaks?
When did this lamp start lighting up? Was any work done on the brakes (or anywhere) just before it started?
Do you drive the car a lot or does it only take you 3 miles to church on Sunday, and stay garaged the rest of the time..
--------

Very usually, the lamp goes on because brake pressure is low, the reasons for which are many.
The brake system is fairly simple and there are a few common problems which cause that lamp to light up. Bad wheel sensors is NOT one of them.
 
The light is always on. The dealer diagnosed it as the speed sensor causing the problem, but couldn't find a part for it (wanted to charge me $460 for it if they could) and a different mechanic that I go see said the the same but can't find a part either.

"So, I was forced to learn about it. It turned out that the problem was a clogged filter hidden inside and at the bottom of the fluid reservoir... fixed for $6 for a junkyard reservoir replacement.."

Did you find the reservoir replacement from a different Mark or an interchangeable part from a different car?

The brakes are fine. I don't live far from work and I usually take the freeways during off hours so I'm not doing that stop and go stuff that messes with the fluid.
 
The local self-service bone yard (Pick & Pull) has had a steady supply of Marks over the years. They come in, are stripped bare, and go. I rarely need to buy anything at a dealer.

I have an '88 LSC but i think the brake fluid reservoir came off an '89 Lincoln.. I don't think it was an LSC. So many parts are interchangeable across years and models and even brand name (like Ford and Lincoln and Mercury) I just search them all 'till I find what I need..

Wheel sensors? Probably a million of those things in the junkyard. Wouldn't surprise me if several different cars used the exact same ones.
-------

I've never needed to resort to it but there are wrecking yard associations. At least one is nationwide. Some are statewide like "The Arizona Automotive Recyclers Association" (AARA)

Google your State and the words wrecking yard or wrecker. Some association will show up in the search.
Then call a local member. If they don't have your part, they'll put out a request to all the other wrecking yards. The part is then shipped to your local dealer.
(There may be "associations" that do not associate for this reason, so ask first.)
----------

I have the Shop Manuals. Surprisingly, each wheel sensor has it's own diagnosis page (mostly various electrical tests.) The main difference in tests is which connector pins are used, because the Left Rear sensor is connected to different pins than is Right Rear, as would be expected.

But from the drawings on these pages, it appears as though each wheel has a particular sensor connector. Connectors may be different.. drawings depicting the Right Rear and Left Rear are certainly different, and perhaps all four sensors are wheel-specific.

I just don't know from experience. But if you choose to find used, junkyard parts, you have been forewarned. :shifty:
Find out from your mechanic (or from his paperwork / receipt) which sensor is bad.... and specify that you want to replace that particular wheel sensor (right or left, back or front).
--------

That lamp is on all the time.. I still don't like this.. My instincts are telling me something. I'm gonna page through this manual and see if there's a simple test you might run to determine if the sensors are at fault.
 
Elessee said:
The local self-service bone yard (Pick & Pull) has had a steady supply of Marks over the years. They come in, are stripped bare, and go. I rarely need to buy anything at a dealer.

I have an '88 LSC but i think the brake fluid reservoir came off an '89 Lincoln.. I don't think it was an LSC. So many parts are interchangeable across years and models and even brand name (like Ford and Lincoln and Mercury) I just search them all 'till I find what I need..

Wheel sensors? Probably a million of those things in the junkyard. Wouldn't surprise me if several different cars used the exact same ones.
-------

I've never needed to resort to it but there are wrecking yard associations. At least one is nationwide. Some are statewide like "The Arizona Automotive Recyclers Association" (AARA)

Google your State and the words wrecking yard or wrecker. Some association will show up in the search.
Then call a local member. If they don't have your part, they'll put out a request to all the other wrecking yards. The part is then shipped to your local dealer.
(There may be "associations" that do not associate for this reason, so ask first.)
----------

I have the Shop Manuals. Surprisingly, each wheel sensor has it's own diagnosis page (mostly various electrical tests.) The main difference in tests is which connector pins are used, because the Left Rear sensor is connected to different pins than is Right Rear, as would be expected.

But from the drawings on these pages, it appears as though each wheel has a particular sensor connector. Connectors may be different.. drawings depicting the Right Rear and Left Rear are certainly different, and perhaps all four sensors are wheel-specific.

I just don't know from experience. But if you choose to find used, junkyard parts, you have been forewarned. :shifty:
Find out from your mechanic (or from his paperwork / receipt) which sensor is bad.... and specify that you want to replace that particular wheel sensor (right or left, back or front).
--------

That lamp is on all the time.. I still don't like this.. My instincts are telling me something. I'm gonna page through this manual and see if there's a simple test you might run to determine if the sensors are at fault.
Click to expand...

Have a similar problem with my 90 LSC. My orange antilock light began to stay on longer and longer after start up. It subsequently stayed on continuously. Brakes stop fine --however the antilock feature does not function. Dealer says antilock system is disabled cause right front sensor is faulty but say that the defalt is regular breaking and is safe. They can't get a new sensor so I'll have to search salvage yards. What I don't understand is, how the sensors could become defective. I thought that they were basically just a permanent magnet sensing the openings on the rotor.
Also, after a crash in 1999 I was told that the sensor on the left front was faulty. That one along with the rotor was replaced. The others are originals.
Hope this adds some information that can be useful.
 
According to the manual, there are "four variable reluctance electronic sensor assemblies".

50 tooth sensor rings are pressed into the front rotors..
The front sensors have an adjustable air-gap between sensor head and toothed ring.
Front air gap is 1.3mm (0.051 inch) and is set using a paper spacer.

The gap on the Rears is less: 1.1mm. Set it with a paper spacer or a feeler gauge. The rear "ring" looks like a toothed gear whereas the front ring looks more like a phonograph record with radial slots cut into it.

"The sensors are adjustable." (T-Bird Turbo Coupe Rear sensors are not adjustable.)
------

"Variable reluctance" implies some wire coils and maybe other electronics are stuffed in there. The Fronts appear to be large and blocky with corners rounded over. On the Rear there's a different drawing.. it's more a short, thin cylinder shape.

From Wikipedia.. Search "Variable reluctance sensor":
A variable reluctance sensor (VRS) is used to measure position and speed of moving metal components. This sensor consists of a permanent magnet, a ferromagnetic pole piece, a pickup coil, and a rotating toothed wheel.

Permanent magnets can lose their strength in a couple ways I know of. One is to heat them beyond a particular temperature (got a special name.. the Curie temperature). Another is by mechanical shock, like whack it with a hammer.. or maybe a rock at 90 mph?
 
Elessee said:
According to the manual, there are "four variable reluctance electronic sensor assemblies".

50 tooth sensor rings are pressed into the front rotors..
The front sensors have an adjustable air-gap between sensor head and toothed ring.
Front air gap is 1.3mm (0.051 inch) and is set using a paper spacer.

The gap on the Rears is less: 1.1mm. Set it with a paper spacer or a feeler gauge. The rear "ring" looks like a toothed gear whereas the front ring looks more like a phonograph record with radial slots cut into it.

"The sensors are adjustable." (T-Bird Turbo Coupe Rear sensors are not adjustable.)
------

"Variable reluctance" implies some wire coils and maybe other electronics are stuffed in there. The Fronts appear to be large and blocky with corners rounded over. On the Rear there's a different drawing.. it's more a short, thin cylinder shape.

From Wikipedia.. Search "Variable reluctance sensor":
A variable reluctance sensor (VRS) is used to measure position and speed of moving metal components. This sensor consists of a permanent magnet, a ferromagnetic pole piece, a pickup coil, and a rotating toothed wheel.

Permanent magnets can lose their strength in a couple ways I know of. One is to heat them beyond a particular temperature (got a special name.. the Curie temperature). Another is by mechanical shock, like whack it with a hammer.. or maybe a rock at 90 mph?
Click to expand...

Elessee,

Many thanks for your helpful information. Now I can imagine how the crash (point of impact front drivers wheel) back in 1999 could have ruined that left front sensor. Since I'm not aware of any significant impacts on the passigner side I am now hoping that my problem is only a spaceing issue that I can adjust (when the weather improves a bit). Otherwise, I'll be looking at the filter in the bottom of the fluid tank on the master assembly (again when the weather improves) Wouldn't want to mess with that old plastic in the cold. Thanks again for your information.
 
I may have missed something here, but the FIRST thing to check is get under and look at it. It has permanent magnet and in time will pick up enough "stuff", metal and otherwise that it can no longer sense - so it sets the light.
 
Blenderhead said:
Let me know which sensor is bad, and I will see if I can locate one for you.
Click to expand...

Many thanks. I'll get back to you after I check the "gap" to see if that could be my problem. Dealership identified the right front as being faulty but I don't think they verified the gap because they used some kind of computer/scanner:) to make their determination.
 
leejoffe said:
I may have missed something here, but the FIRST thing to check is get under and look at it. It has permanent magnet and in time will pick up enough "stuff", metal and otherwise that it can no longer sense - so it sets the light.
Click to expand...

Leejoffe,

Thanks. That was the second thing I tried after bleeding the system. Pulled the wheels and roters -- yep the sensors were allloaded with bits of rust. In my case careful cleaningl didn't solve the issue.
 
....however the antilock feature does not function.
Dealer says antilock system is disabled cause right front sensor is faulty but say that the defalt is regular breaking and is safe.....

Lincolnlov,
Don't you bother with the filter in the reservoir. That problem was unusual, mentioned only to illustrate one weird example of what can cause the ABS lamp to light up.
The clogged filter starved the hydraulic pump. The pump then ran continuously because no pressure was building. The pump's motor's heat sensor shut it all down till it cooled off, and in the meantime there was NO power brakes at all.

(If you're determined to check it, just pull the rubber hose off the reservoir's underside. Fluid should flow out.

BTW, I had my car serviced today.. Front brake rotors turned.. and mentioned that reservoir filter clogging up. The mechanic said it was probably due to someone topping off the reservoir with the wrong brake fluid, and contaminating it.)
-----------

Another, more common example, is the relay that powers the pump's motor. That relay's contacts carry high current, spark a lot, deteriorate and tend to stick closed.

But pressure is adequate! The "normal" brakes work fine as does ABS!

However, the motor is forced to run continuously, it overheats and it shuts off (for a couple minutes), and a fault is detected. And the lamp lights up periodically.
The obvious symptom is the pump-motor runs whenever the ignition switch is ON. But tap the relay and the contacts separate and the motor shuts off.
[edit] That's not exactly true. The motor could run "whenever the ignition switch is ON", but road and engine vibration will normally jar the relay's stuck contacts loose, and the motor (and warning lamp) will turn off. [ed]

Here the cure is a new relay. (They run about $23 at Lincoln dealers, btw)
-------

Your problem is very likely as the dealer diagnosed.. Having no ABS, while "normal" power brakes work, does seem to pinpoint some component specific to the ABS system.

One thing that bugs me (and should bug you) is that if some component of the normal brake system failed, you'd get no warning.. because the only warning lamp capable of notifying you of further trouble is already lit up.
 
"One thing that bugs me (and should bug you) is that if some component of the normal brake system failed, you'd get no warning.. because the only warning lamp capable of notifying you of further trouble is already lit up. "

Getting a used part from the Junkyard bugs me, but not as much as what you said so I'm gonna see what if anything I can find at the bone yard. I'll keep you posted, thanks again
 
Elessee said:
....however the antilock feature does not function.
Dealer says antilock system is disabled cause right front sensor is faulty but say that the defalt is regular breaking and is safe.....

Lincolnlov,
Don't you bother with the filter in the reservoir. That problem was unusual, mentioned only to illustrate one weird example of what can cause the ABS lamp to light up.
The clogged filter starved the hydraulic pump. The pump then ran continuously because no pressure was building. The pump's motor's heat sensor shut it all down till it cooled off, and in the meantime there was NO power brakes at all.

(If you're determined to check it, just pull the rubber hose off the reservoir's underside. Fluid should flow out.

BTW, I had my car serviced today.. Front brake rotors turned.. and mentioned that reservoir filter clogging up. The mechanic said it was probably due to someone topping off the reservoir with the wrong brake fluid, and contaminating it.)
-----------

Another, more common example, is the relay that powers the pump's motor. That relay's contacts carry high current, spark a lot, deteriorate and tend to stick closed.

But pressure is adequate! The "normal" brakes work fine as does ABS!

However, the motor is forced to run continuously, it overheats and it shuts off (for a couple minutes), and a fault is detected. And the lamp lights up periodically.
The obvious symptom is the pump-motor runs whenever the ignition switch is ON. But tap the relay and the contacts separate and the motor shuts off.
[edit] That's not exactly true. The motor could run "whenever the ignition switch is ON", but road and engine vibration will normally jar the relay's stuck contacts loose, and the motor (and warning lamp) will turn off. [ed]

Here the cure is a new relay. (They run about $23 at Lincoln dealers, btw)
-------

Your problem is very likely as the dealer diagnosed.. Having no ABS, while "normal" power brakes work, does seem to pinpoint some component specific to the ABS system.

One thing that bugs me (and should bug you) is that if some component of the normal brake system failed, you'd get no warning.. because the only warning lamp capable of notifying you of further trouble is already lit up.
Click to expand...
ELESSEE,

Thanks for all your additional info.
Last summer I replaced my accumulator because my pump would come on after every 2 or 3 touches of the brake pedal. Now I can hit the brakes 6-8 times before the pump comes on. When I had the old accumulator in place I'd get both the red and orange brake lights coming on at times. Some times several months ago, post accumulator replacement, my orange light would appear. If I turned the key off and re started the car the orange would flicker then after 15 seconds or so it would go off and I had the antilock function. Tried it on a dirt road and it pulsed just fine. Now I only have orange on -- though its on all the time, and my antilock system does not pulse with hard breaking on a dirt surface.
So, once a warm weekend appears I'll check the sensor spacing and also see if fluid runs freely from the reservoir at the rubber hose connection. I'll keep you all posted.
 
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