how to test anit-lock brakes?

mostsmooth

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Hi all,
95 gt
i am checking everything i can about the car since it had been sitting for a long time and also because i just want to learn how everything works.
i am about to open the differential to replace the spider gears, and while i am at it i will try and do the axle bearings and seals.
to do the bearings and seals, i need to take out the axle, and if im taking out the axle, i thought it would be a good time to replace those abs gear things that are pressed onto the axle. i have been under the car frequently these days looking around and when i looked at those gears, they seemed a bit worn, at least the one i looked at. i have no idea what they look like new though.
so, i thought if i hit the brakes real hard, i could check if the abs is working. i hit the brakes real hard and the tires skidded, and i didnt feel any abs pulsing that i would expect.

truth be told, i dont know exactly how the system works and maybe trying to test it out like this on dry pavement is pointless.

there are no warning lights on the dash.

is there a way to check if my abs is functioning properly?

Thanks
 
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Mustang5L5

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Are you sure the car has ABS? I think it was optional on a 1995 GT.

First thing to check is the ABS light. Turn the key to ON but don't start the car. The ABS light should come on and then go off. That tells us you have ABS, and that the system is passing all it's self checks. If the light doesn't come on, then you do not have ABS, or there is a system fault and the bulb is burned out therefore not alerting you that the system is disabled.

If that all passes, probably the easier way to "test" it is to find a safe space and try to brake hard on loose gravel or try it when there's a light/misting rain.

1995 era ABS was rather clunky and slow as chips then were not as fast as they are today. You should be able to easily feel the pedal pulsations if you lose grip while stopping.
 
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mostsmooth

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Are you sure the car has ABS? I think it was optional on a 1995 GT.

First thing to check is the ABS light. Turn the key to ON but don't start the car. The ABS light should come on and then go off. That tells us you have ABS, and that the system is passing all it's self checks. If the light doesn't come on, then you do not have ABS, or there is a system fault and the bulb is burned out therefore not alerting you that the system is disabled.

If that all passes, probably the easier way to "test" it is to find a safe space and try to brake hard on loose gravel or try it when there's a light/misting rain.

1995 era ABS was rather clunky and slow as chips then were not as fast as they are today. You should be able to easily feel the pedal pulsations if you lose grip while stopping.
well, i saw the abs gear on the axle, so i assumed so, plus i seem to recall having it, but i checked my window sticker and i did get the option.
i ran a code check recently and didnt see anything about abs. i will check if the light come on and off as you mentioned.
then i will wait for some rain

thanks
 

Mustang5L5

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SOunds like you do have ABS then. In that case, check for illumination of the ABS light when you cycle key to on. This will verify it's not burned out and masking a fault that is turning the ABS system off
 

rockyracoon

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Perhaps someone else more knowledgeable can chime in but I don't think any abs codes will show up from the icm. I thought that was a separate module.
 

mostsmooth

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SOunds like you do have ABS then. In that case, check for illumination of the ABS light when you cycle key to on. This will verify it's not burned out and masking a fault that is turning the ABS system off
When I turn the key, the abs light comes on and goes off in what appears to be a normal way.
 

Mustang5L5

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Then all indications are your abs system should work as the internal self- test is apparently being passed. Go find some loose gravel or better yet what for some misty rain in an oily parking lot and test it out. Should feel the pedal pulsate as you brake hard
 
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7991LXnSHO

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In a system from 95, I’d be surprised if the pedal pulses were not accompanied by a low pitch, loud noise when the ABS is working.
 

revhead347

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First off, the ABS in a 1995 GT works absolutely great. You can absolutely feel it pulsing in the pedal when it interferes, and I can bet you it drops a near perfect 80/20 ratio. For decades almost all the ABS systems were the Bosch design and unchanged between manufacturers. To say that the ABS was less than adequate in the 1995 Mustang would mean that the ABS was less than adequate in a 1995 Porsche 911.

The reluctor rings you are talking about do not wear out. They might get dirty, they might get damaged, but they don't wear out, because there is nothing to wear against. They should be taken off and reinstalled with a press. You are more apt to do damage to them trying to install new ones without the proper tools. Most importantly, the ABS computer is not stupid. If it was getting a bad speed signal from one of the wheels, it would throw an ABS light. You don't need to check the codes, a bad speed sensor input generates a continuous ABS light. Leave them alone.

Kurt
 
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mostsmooth

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First off, the ABS in a 1995 GT works absolutely great. You can absolutely feel it pulsing in the pedal when it interferes, and I can bet you it drops a near perfect 80/20 ratio. For decades almost all the ABS systems were the Bosch design and unchanged between manufacturers. To say that the ABS was less than adequate in the 1995 Mustang would mean that the ABS was less than adequate in a 1995 Porsche 911.

The reluctor rings you are talking about do not wear out. They might get dirty, they might get damaged, but they don't wear out, because there is nothing to wear against. They should be taken off and reinstalled with a press. You are more apt to do damage to them trying to install new ones without the proper tools. Most importantly, the ABS computer is not stupid. If it was getting a bad speed signal from one of the wheels, it would throw an ABS light. You don't need to check the codes, a bad speed sensor input generates a continuous ABS light. Leave them alone.

Kurt
based on this and looking at it up close today, i am now under the impression the little ABS thing i need to loosed up so i can get teh axle off is a sensor that sensed the ridges in the gear thing i thought may be worn. it had a good coating of some dirt grease mixture that i am guess was slowly leaking out of the axle seal. just a guess at this point. but yeah, if that little abs thing is a fixed position sensor, then yeah there isnt anything to wear out. not on the gear anyway
 

mostsmooth

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Then all indications are your abs system should work as the internal self- test is apparently being passed. Go find some loose gravel or better yet what for some misty rain in an oily parking lot and test it out. Should feel the pedal pulsate as you brake hard
whelp, i replaced some spider and side gears today and that requires taking out axles, which requires taking out the ABS sensor. both of mine werent budging and needed some persuasion. now my ABS light is on and staying on. i assume i broke at least one of them. i wont be driving the car until tomorrow night at the earliest, so cant check if maybe it will go out on its own. im sure i broke it. damn

anybody know how difficult these are to replace? seems it is one long wire that connects somewhere, but not sure where.

thanks
 

revhead347

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You have to remove the bottom back seat to get to the connector. There are 2 white buttons under the rim of the seat that you push to unlock it, and it pops up. Should be a sound carpet just thrown in under there too. The problem is not replacing them, it's finding them. Someone found them on here recently. I think I might be able to look that up if you can't find a replacement one. If you find replacements, please post up so I can add it to my resource list.

Kurt
 

mostsmooth

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You have to remove the bottom back seat to get to the connector. There are 2 white buttons under the rim of the seat that you push to unlock it, and it pops up. Should be a sound carpet just thrown in under there too. The problem is not replacing them, it's finding them. Someone found them on here recently. I think I might be able to look that up if you can't find a replacement one. If you find replacements, please post up so I can add it to my resource list.

Kurt
they seem to have both sides for rear at least.
 
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mostsmooth

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There are codes.

you need to ground the abs test connector and the abs light will flash the codes

am trying to do this today, and there is no orange and white wire in my connector. i dont even care if it is orange and white, there is no wire in the spot (#2)where the diagram i found on veryuseful.com says there should be for the abs. is this something particular to 95 gts?
 

Mustang5L5

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Are you using the abs connector plug and not the eec4 diagnostic plug? The abs plug is located next to the fuse box.

junp pin 2 to 5

0128A368-5B8F-4B5B-9B5F-E4F10C804DE0.jpeg
 

mostsmooth

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ok so i did the check.
i got a 19.
apparently that is the anit lock control module.
is it possible that i have a bad sensor and it defaulted to this error message?
i ask because prior to me changing the spider grears, i had no abs light at all and then immediately afterwards the light was coming on and staying on. the only thing that changed was that i had to bang on the sensors a little to get them out.
seems like too much of a coincidence that the 'control module' has a problem all of a sudden.
 

Mustang5L5

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Test the rear sensors with a voltmeter. Set it to resistance and measure in ohms. Measure each sensor and see what you get.

I do not know the acceptable value offhand, but open would indicate a bad sensor. They frequently bulge due to moisture/corrosion.

There are also tests for the modules. I believe there might be one such procudeute in the link above