99 SVT - Breaks fine but abs kicks in almost every stop

[xbox4life]

As you can see above my car is freaking out

while it stops consistently and safely (so far) there is something not right here

when turning and stopping it is especially noticeable for reasons unknown to me thus far

the car had all new pads and roaters put on in the fall but the issue only started happening a couple months after

when i get on the breaks it feela like the pedal goes soft about half way into slow down .. then i can feel the abs pump go crazy once i let up on the break pedal

i just put on my summer rubber .. and all wheels spin without issues and nothing i seen yesterday gave me anything to go on

please help

 

[crewchiefpro]

When you have a "brake" problem where the ABS fires when it should not, you should get the car scanned for codes first.

I would get your hands on a repair manual. There are only a few parts that make up the ABS so it should be easy to follow the codes to the correct repair.

 

[BrApple]

First check that the work done to the brakes was done correctly. Are all of the bolts tight and torque to specification? Are the front caliper springs installed and installed correctly? Is there any damage to the suspension that might be causing an issue?

If the pedal is going "soft" had the system been bleed correctly? Was air pushed into the system when the brakes where changed?

Where the summer wheels torqued on correctly?

 

[striker2]

to add to what BrApple said, also inspect the tone rings on the axles (for the front and the hubs for the rear). if one of them is broken it can cause the ABS module to not get a good reading on that wheel speed and will engage the ABS.

 

[amc49]

If a caliper or wheel cylinder has started to leak to get leaked fluid on a pad or shoe then all the gradual braking ability of the friction surface goes right out the window. The brake then begins to simply lock up solid with no modulation at all and very little pedal effort. That will flip the ABS out and it then begins to work way too early and too much because the brake is either off or locked with no in between. I had the problem on a drum brake rear Contour and renewing all the brake there cured it and ABS went back to working fine.

 

[cclngthr]

First check that the work done to the brakes was done correctly. Are all of the bolts tight and torque to specification? Are the front caliper springs installed and installed correctly? Is there any damage to the suspension that might be causing an issue?

If the pedal is going "soft" had the system been bleed correctly? Was air pushed into the system when the brakes where changed?

Where the summer wheels torqued on correctly?

With the ABS system, you have to cycle the ABS module to get the air out of the system.

It sounds to me that there could be air lodged in the ABS module, and acts like it locks up momentarily, then when it is released, the module thinks the brakes are still pressurized and cycles the module. Air could be ahead of the module and it is being pushed into the module, which makes it act up. I use an electronic ABS cycler controller when I bleed brakes on cars with that system. Very difficult to expel air from the system without it.

 

[xbox4life]

Thanks to everyone who chimed in - this was the first time i ever had someone else do my breaks ... and here we are (interestingly enough when i had them done and the guy said he had to cut off at least one of the roters ... hmmm)

the car passes a visual inspection .. i looked / tugged on everything and there isn't anything that made me think something wasn't installed correctly

i have now swapped out my summers / winters / back to summers again since the brake work ( once at a garage and twice in my driveway - and can confirm the wheels are torqued down correctly

Now the pedal isnt soft .. but when slowing from speed is gets softer as it steps down (that's the best way i can describe it - its fine then goes a step lower .. then a step lower .. then a step lower .. not anywhere near the floor .. but the way it steps down .. isnt normal at all) and then i hear / feel the abs kick in

air lodged in the abs module? .. i have bleed my brakes on my other svt before .. and dont recall doing anything like that specific to abs .. but i do get why you say there might be some air in the line

ill scan for codes when the wife gets home and respond back when i get a reading

 

[cclngthr]

Thanks to everyone who chimed in - this was the first time i ever had someone else do my breaks ... and here we are (interestingly enough when i had them done and the guy said he had to cut off at least one of the roters ... hmmm)

the car passes a visual inspection .. i looked / tugged on everything and there isn't anything that made me think something wasn't installed correctly

i have now swapped out my summers / winters / back to summers again since the brake work ( once at a garage and twice in my driveway - and can confirm the wheels are torqued down correctly

Now the pedal isnt soft .. but when slowing from speed is gets softer as it steps down (that's the best way i can describe it - its fine then goes a step lower .. then a step lower .. then a step lower .. not anywhere near the floor .. but the way it steps down .. isnt normal at all) and then i hear / feel the abs kick in

air lodged in the abs module? .. i have bleed my brakes on my other svt before .. and dont recall doing anything like that specific to abs .. but i do get why you say there might be some air in the line

ill scan for codes when the wife gets home and respond back when i get a reading

Air in the ABS module is possible, and getting the air out is very difficult, especially on Fords, and especially if the air is located in front of the module (where the brake line from the master cylinder goes into the module). The Taurus from 1996-2007 are known to have air trapped in the system, and the only way to get it out is use an electric controller that cycles the ABS pump as you vacuum bleed the brake system.

 

[blu_fuz]

Make sure the ABS sensors are actually pointing at the tone ring on the hub. If not, the ABS will kick in almost every time you brake and you can even here it trying to function when you are at speed.

 

[cclngthr]

Make sure the ABS sensors are actually pointing at the tone ring on the hub. If not, the ABS will kick in almost every time you brake and you can even here it trying to function when you are at speed.

Those sensors are no where near the brake rotor, and typically are not touched when servicing the brakes (they are behind the hub). Even if the mechanic did have to chisel off the rotor due to rust, (seen that happen on many cars before), the sensor should not have been disturbed.

The way I understood it, the pedal goes down in a step fashion when braking, not pulsing up and down in a normal brake ABS function. It sounds (from that) that the system has air trapped in the ABS module, or just ahead of it, and air is pushed into the module which can make the pedal drop in a step manner.

Easiest solution is to read the codes while the car is driven to see which wheel is affected, or which end is affected.

It also could be a bad ABS module as well; they can do the same thing; where the system activates prematurely or at the wrong time. It sounds to me that there is air trapped in the system. However, if that is not the case, a more thorough test of the sensor and module is required. Could be either or both.

 

[amc49]

It is very difficult to get air inside the abs module unless something is wrong with it. It only cycles when it detects wheel lockup and air in lines moves the system further away from that as the air compresses and then much harder to lock wheels up at that point. Once you get air in one though you WILL need to cycle the module on to get it out as it shuts off to the rest of the system in normal use or off, thus trapping any air inside it. Why you can bleed the brake systems all day long and not have to fuss with the abs, the system is transparent to the rest of the hydraulic system until it turns on. I have never bled an abs in my life and the cars happily motor on and the abs works fine.

Air can only get in abs module if it is on at the time air is present and hard to do as said, or the module is defective to be open to the system. I myself can only say I've never seen abs even think about working with air in the lines, the wheels will not lock then to switch it on. I would say that if the abs is trying to come on with clear air in the system then the module is defective. Of course there will be those who show up with cars in conditions that will always make you scratch your head...........

 

[cclngthr]

It is very difficult to get air inside the abs module unless something is wrong with it. It only cycles when it detects wheel lockup and air in lines moves the system further away from that as the air compresses and then much harder to lock wheels up at that point. Once you get air in one though you WILL need to cycle the module on to get it out as it shuts off to the rest of the system in normal use or off, thus trapping any air inside it. Why you can bleed the brake systems all day long and not have to fuss with the abs, the system is transparent to the rest of the hydraulic system until it turns on. I have never bled an abs in my life and the cars happily motor on and the abs works fine.

Air can only get in abs module if it is on at the time air is present and hard to do as said, or the module is defective to be open to the system. I myself can only say I've never seen abs even think about working with air in the lines, the wheels will not lock then to switch it on. I would say that if the abs is trying to come on with clear air in the system then the module is defective. Of course there will be those who show up with cars in conditions that will always make you scratch your head...........

I did a bit of research on this and did find the module can (on some level) cycle erratically if the air is just ahead of the module, and as it starts cycling, air gets lodged into the module, which makes it cycle even more erratic. I also found that a bad module can either not cycle (making the brakes lock up prematurely) or cause it to cycle when it shouldn't. I personally would flush the entire brake system with new fluid, including cycling the ABS to do it correctly; there are hidden pockets where fluid is stored in the module that is used when the system cycles.

 

[amc49]

It may possibly suck air on the power up they do when the car first rolls off. The motor runs up for a second as an operating check.

Pull main power connector to abs and then bleed the brakes normally, you should be able to get full operation and working fine, that would point to abs issue unless an abs port is stuck open to trap air in it. The default should be closed.