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ABS brake experts


wild one
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I needed to make a trip the other day to my local small town bank driving my 2003 Ranger. There are a couple stop signs in town and I braked and stopped normally at each. My bank is right across from a T intersection where I stopped and brakes seemed fine. There is angle parking in front of the bank with fortunately a sloped curb about 18" high. I was probably going five miles an hour when I applied the brakes and at first I think they slowed me a bit, then nothing. I remember a racket coming from under the hood as I began to thing my bank was going to have a new drive in door. Thankfully the tall curb stopped me when I started up over it. I backed off the curb ans sat there a second hoping no one had seen  this. Wrong. Local gal who is an emt came over wondering if I was all right, or more likely if I was drunk. She said she was behind me and had heard a loud racket then saw me hit the curb. Street repair crew down the street are all watching now too. I check under the hood , brake fluid is full,can see no damage, all looks fine. I never told the banker I had almost given him a new drive in door and when I came out the streets were empty so I tried the brakes and all seemed fine. I drove home very carefully and when I got home tried the brakes many times and they seem normal.

 I am probably about due for a brake job anyway,so I plan to tear this thing apart and see if I can find a problem as I have no confidence in driving it right now. I could have been in a very bad situation. This makes me think what if I had been in a bad accident and I said I lost my brakes and some one checks them out and they work fine? I am sure I have an ABS problem that may be difficult to find and maybe not worth the cost in a truck with 250,000 miles, but I do not feel confident driving it til I do. Makes me wonder how many people have been in accidents or even killed because of some little intermittent or one time malfunction that is never known.

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I grew up when "pumping the brakes" was part of learning how to drive. 

After ABS caused my 99 Dodge to roll through a T intersection at the end of my driveway, over a small embankment and through a fence and some small trees, I found I was able to just unlpug the ABS on the left fender well. 

There are times I may need to lock up all six tires and want to have that capability 

I want to be in control of how much brake is applied. 

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Not sure i have ever heard of abs causing brakes not to work. Always thought it either worked or did not and you were without abs but normal brakes would work. Am i wrong in that assumtion?

I dont really care for abs either. Hated them when i got first vehicle with them. 

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1 minute ago, iowaboy1965 said:

Not sure i have ever heard of abs causing brakes not to work. Always thought it either worked or did not and you were without abs but normal brakes would work. Am i wrong in that assumtion?

I dont really care for abs either. Hated them when i got first vehicle with them. 

If there is a pulse where the brakes are applied and released quickly could they stick on release???? HOnestly don't know. My situation, they worked as they should but if i could have locked up the tires in the soft sand, I could have slowed enough to make the corner. First ABS pickup for me too. 

I was MADD (Mad A$$ed Dually Driver) as turkey hunters on top of the canyon were raining down pellets on our tin roof and I was headed up there to teach a hunter safety course. 

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So, here are some simple answers.....

*ABS cannot easily be "removed" or bypassed.  It can be disabled, but that is no guarantee that it won't or can't still malfunction.  It is very difficult to totally remove an ABS control module from a "modern" vehicle.

*ABS systems can and do malfunction as described above.  No, they don't always just "work or don't work". 

*Diagnosing something like this one time issue is extremely difficult as it may or may not be able to be duplicated. 

*Simply pulling the fuse if a bad idea.  Generally there is always something else also powered by each circuit.  Not always, but generally. 

 

As a tech, I can't suggest that you bypass a manufacturer safety device.  But here is a tip that you can use for "testing".  Instead of pulling the fuse, find and unplug the ABS Module, the actual unit that the brake lines go in to.  If you can't find it, then you shouldn't be trying to work on it.  With it unplugged, see if you can duplicate the error.  I could go into detail on what may or might not be wrong with your system, but the simple fact is that unless you own a pretty good scan tool, then you won't be able to read any data that you have to see to make a diagnosis.  My recommendation is to take it to your mechanic, or local Ford garage to be repaired.  Everyone here will hate that answer, but most people (almost no one) own the tools to diagnose modern cars anyway, so no reason to sit around and make guesses.  Besides, Ford's data stream is difficult to interpret anyway, if you can even see it at all.  FoMoCo's diagnostic data has always been sub-par in my opinion.  When Chrysler and GM were giving lots of hard data in their data streams, Ford wasn't.  Their code pulling system is a joke, as there are KOEO and KOER test that have to be run to get all the codes.  Take it to a dealer or a shop, or do some testing with the module unplugged.  Even with it unplugged, it can still malfunction, just so you know. However, when it does it won't make noises under the hood.... the brakes just won't work. 

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On early 2000's GM trucks, wheel speed sensor failure or loss of signal causes this behavior, especially when you've lost more than one and especially if it is in the front.  On these trucks, the ABS does a self test on start up when the vehicle is removed from park or neutral, the truck is in motion, and the brake is applied.  After a stop or two with one bad sensor, it will usually recognize the issue (3 wheels moving, 1 not) and turn on the ABS warning light and disable ABS until the next key-on cycle.  When two sensors fail, or one fails and the second is intermittent on the front axle, the truck randomly engages the ABS and the pedal nearly drops to the floor because the data it receives indicates that there are wheels at zero rpm and it tries to direct the line pressure away from those wheels.  When both bad sensors are on the front, the brakes are nearly non-existent because the rear drums have very limited braking power.  On a pickup there is very little weight in the rear, so the braking force is usually heavily biased toward the front.

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Above said is a very good explanation of the general workings of abs brake systems. Wheel sensors will throw it into abs mode. I dislike how once it is activated the pedal goes to the floor and you basically are out of control of the brakes. Best thing to do is release brakes and re apply if you have time to. Are you getting an abs light?  Very good scan tools are the only way to get codes from abs computer. Good luck

Mark

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5 hours ago, chadd said:

On early 2000's GM trucks, wheel speed sensor failure or loss of signal causes this behavior, especially when you've lost more than one and especially if it is in the front.  On these trucks, the ABS does a self test on start up when the vehicle is removed from park or neutral, the truck is in motion, and the brake is applied.  After a stop or two with one bad sensor, it will usually recognize the issue (3 wheels moving, 1 not) and turn on the ABS warning light and disable ABS until the next key-on cycle.  When two sensors fail, or one fails and the second is intermittent on the front axle, the truck randomly engages the ABS and the pedal nearly drops to the floor because the data it receives indicates that there are wheels at zero rpm and it tries to direct the line pressure away from those wheels.  When both bad sensors are on the front, the brakes are nearly non-existent because the rear drums have very limited braking power.  On a pickup there is very little weight in the rear, so the braking force is usually heavily biased toward the front.

I have this problem on my 06 GMC.

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I know a lot of you guys are down on ABS systems, but they require the exact OPPOSITE technique from what you're used to, to use them properly in a skid situation. They're designed and tailored to the natural human reaction of pushing on the brakes harder when you get into a skid/slide. So, that's what you need to do. Throw out your decades of habit and just "stomp and steer."

It is entirely possible that you hit a small patch of oil or some other slick spot, causing a wheel to skid, triggering the ABS event. I've seen guys go down on their motorcycles on a patch of oil the size of a quarter, so it doesn't take much.

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I pull the fuse on every ABS piece of crap I own, never any bad side effects. My 2010 Silverado also got the fuse for the traction control jerked after a trip down a muddy road had smoke billowing out the wheel wells after 15 miles at 15 MPH right to the floor. It came right to a grinding halt twice on that trip!

 

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If you go in to do brakes check all your connections to the front hubs: my 1997 GMC 1500 did that where it would randomly pulse the ABS on dry pavement which does make it harder to stop when the brake pressure doesn't need to be backed off. I pulled the fuse to keep it from doing it to get home; I eventually pulled a front wheel off and found the clip holding the wire going to the hub for the ABS sensor had gotten bent and the wire rubbed through on the rim and was randomly shorting out and sending a signal to trip the ABS. Since you said it did it while parking I have seen some do that same sort of thing while at full lock on the steering if a hub/wheel bearing starts to go bad. You get movement inside the hub while turning and it will make the sensor have a messed up reading and trip the ABS sometimes. My Impala started throwing ABS codes and tripped a few times and turned out to be bad/worn front wheel bearings so I installed new hubs and was good to go. So, first thing I would check all wires and connectors for the wheel sensors and check for play in the hubs if it has the unit hubs with the sensors in them.

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What’s the chances he just lost a pad? I had one fall out on a new truck with 13 or 15k on it once. Pad separated and fell out, pedal hit the floor, I pumped fast, abs went nuts. I’d start simple and lift calipers and pull drums.  The noise being h athe d....maybe metal to metal, maybe the tracks plastic front end scuffing the curb.? Hard to say but  Nobody looks until the hear things happen.  

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1 hour ago, cgage said:

If you go in to do brakes check all your connections to the front hubs: my 1997 GMC 1500 did that where it would randomly pulse the ABS on dry pavement which does make it harder to stop when the brake pressure doesn't need to be backed off. I pulled the fuse to keep it from doing it to get home; I eventually pulled a front wheel off and found the clip holding the wire going to the hub for the ABS sensor had gotten bent and the wire rubbed through on the rim and was randomly shorting out and sending a signal to trip the ABS. Since you said it did it while parking I have seen some do that same sort of thing while at full lock on the steering if a hub/wheel bearing starts to go bad. You get movement inside the hub while turning and it will make the sensor have a messed up reading and trip the ABS sometimes. My Impala started throwing ABS codes and tripped a few times and turned out to be bad/worn front wheel bearings so I installed new hubs and was good to go. So, first thing I would check all wires and connectors for the wheel sensors and check for play in the hubs if it has the unit hubs with the sensors in them.

 

9 hours ago, chadd said:

On early 2000's GM trucks, wheel speed sensor failure or loss of signal causes this behavior, especially when you've lost more than one and especially if it is in the front.  On these trucks, the ABS does a self test on start up when the vehicle is removed from park or neutral, the truck is in motion, and the brake is applied.  After a stop or two with one bad sensor, it will usually recognize the issue (3 wheels moving, 1 not) and turn on the ABS warning light and disable ABS until the next key-on cycle.  When two sensors fail, or one fails and the second is intermittent on the front axle, the truck randomly engages the ABS and the pedal nearly drops to the floor because the data it receives indicates that there are wheels at zero rpm and it tries to direct the line pressure away from those wheels.  When both bad sensors are on the front, the brakes are nearly non-existent because the rear drums have very limited braking power.  On a pickup there is very little weight in the rear, so the braking force is usually heavily biased toward the front.

Both of you are talking about GM, who uses Kelsey Hayes to build their ABS system.  Ford builds their own as I recall.  While all ABS systems are similar, they are not the same.  You will find that GM systems suffer from a common problem that others do not.  Be careful giving advice with limited experience. 

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1 hour ago, R Pope said:

I pull the fuse on every ABS piece of crap I own, never any bad side effects. My 2010 Silverado also got the fuse for the traction control jerked after a trip down a muddy road had smoke billowing out the wheel wells after 15 miles at 15 MPH right to the floor. It came right to a grinding halt twice on that trip!

 

I'm glad you have had no issues pulling fuses.  However, on some vehicles disabling the ABS system can also cause loss of other important devices.  I had someone to pull the ABS fuse just a day or two ago due to a malfunction.  Pulling the fuse also shut off his speedometer.  I've seen it cause loss of other things as well. 

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49 minutes ago, J-Mech said:

Slim to none.

Neighbors wife lost one last week. ‘18 Oldsmobile suv, the bigger one, under 10k on it. She pulled in, given, she wasn’t hearing anything over the radio, but we could hear it. Must have just happened as it hadn’t scufffed the rotor up yet, just lightly. Inside pad looked looked new, outside pad ceramic material was MIA.  

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28 minutes ago, stronger800 said:

Neighbors wife lost one last week. ‘18 Oldsmobile suv, the bigger one, under 10k on it. She pulled in, given, she wasn’t hearing anything over the radio, but we could hear it. Must have just happened as it hadn’t scufffed the rotor up yet, just lightly. Inside pad looked looked new, outside pad ceramic material was MIA.  

Yes it happens.  Not likely what cause the above malfunction though.  Once a pad is lost, the brake system won't later "function normally".  It always blows the piston out of the caliper which causes fluid loss and you have no pedal.  Only in very rare instances is the piston long enough not to blow out when a pad is lost. 

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Thanks very much for all of the replies. After also checking some other forums  it seems under certain circumstances the ABS can cause a low speed brake loss or what seems like a brake loss. I have no codes showing until I unplugged the ABS unit and now my ABS light is on. All other functions seem to work and brakes seem normal. I plan on a complete exam of the brakes and to look for any obvious faults before I take it anywhere again. A seventeen year old truck with 250,000 plus miles could easily wind up with a bigger bill than what the truck is worth at the local Ford dealer. I have two sons in the ag-construction service area and even with probably some of the worlds best diagnostic equipment sometimes it comes down to an expensive guessing game. I have been considering trading or selling the truck for something newer but in its present condition it would probably wind up on some dealers lot and a unsuspecting buyer could get hurt.

 ABS moules appear to be very expensive and I too have had bad results on gravel roads with ABS. I am considering removing the ABS and re plumbing everything like my old rangers without ABS.

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1 hour ago, wild one said:

I am considering removing the ABS and re plumbing everything like my old rangers without ABS.

Good luck with that.  I think you will quickly find that brake lines don't match sizes, you won't have a proportioning valve, fittings are Ford specific and the lines you need to attach to are in very difficult to access locations.  It's not as simple as people think it would be.  It's easier to change an ABS control module than it is to remove it.

Don't automatically assume that the fault is in the module, the most expensive component.  You could just have a bad wheel bearing. 

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