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Car Forum / Ford / Ford Trucks / October 20071998 F150 4X4 - ABS question
It seems like my ABS has stopped working. I'm getting lockup in the rear, one or the other, or both rear wheels tend to want to lock up when braking. There is no heat build up in the brakes so I assume that the brakes are not dragging all the time, the ABS light comes on for a few seconds on start up as normal and does not stay on at any time. I thought at first that it could be the emergency brake not releasing but again, no heat build up like a dragging brake shoe, also no smell of burning brakes. Is there an ABS module or something that can fail without turning on the light? Thanks. Del. PS. Please be kind, I haven't done a brake job in at least 15 years. I plan on taking it into the dealer for repair but would like a bit of info before I go in. Thanks. Del. > It seems like my ABS has stopped working. > I'm getting lockup in the rear, one or the other, or both rear wheels [quoted text clipped - 12 lines] > > PS. Please be kind, I haven't done a brake job in at least 15 years. I believe your truck has 3-channel ABS. If true, this means that the rear brakes are controlled as one while the front brakes are controlled individually. For ABS to kick in on the rear, both wheels would have to lock. 4-channel systems will modulate each corner separately, and this would keep the rear wheels from locking. But with a 3-channel system, it is possible for one rear brake to lock and not have the ABS kick in because to modulate the brake that is locked would aslo modulate the brake on the other side that is doing its job, albeit on a lesser level. In an instance like this, I think the corrective action is to adjust the rear brakes so that they work together. It sounds like one brake is working better (sooner) than the other one, and it can lock before the other brake activates. >I plan on taking it into the dealer for repair but would like a bit of > info before I go in. [quoted text clipped - 18 lines] >> >> PS. Please be kind, I haven't done a brake job in at least 15 years. > I believe your truck has 3-channel ABS. If true, this means that the > rear brakes are controlled as one while the front brakes are controlled > individually. For ABS to kick in on the rear, both wheels would have to > lock. 98 F150 has rear ABS only. >> I believe your truck has 3-channel ABS. If true, this means that the >> rear brakes are controlled as one while the front brakes are controlled >> individually. For ABS to kick in on the rear, both wheels would have to >> lock. > > 98 F150 has rear ABS only. Okay. To control each tire separately, there would need to be two brake pipes leading to the rear axle. If there is only one brake pipe -- hard line that carries brake fluid -- then both rear wheels would need to lock before the ABS kicks in. If there are two brake pipes, then I do not know what the problem is. Sorry. > "david" <none@nospam.com> wrote in message >> 98 F150 has rear ABS only. > [quoted text clipped - 7 lines] > If there are two brake pipes, then I do not know what the problem is. > Sorry. Are there sensors at each wheel in the rear-only ABS? If that's the case, both wheels may not need to lock to activate the ABS. One wheel lockup would trigger the ABS at both wheels. This is just a guess on my part, but it seems to me it would be more practical to trigger the ABS for a minimum of one wheel lockup. >> "david" <none@nospam.com> wrote in message > [quoted text clipped - 15 lines] > it seems to me it would be more practical to trigger the ABS for a minimum > of one wheel lockup. I follow your logic, but I think it is flawed. If one tire is locked but the other is not, if the ABS kicks in, then the unlocked tire will work even less than it is already working. That seems to me to be a serious problem. One does not want too much braking, but too little braking is as bad or worse. I agree that having both tires in a skid is bad, but having one brake work less so that the other does not skid is even worse. The point of ABS is to keep the back end from coming around, but if one of two tires is not skidding, the back end will remain controllable and ABS is not needed. >>> "david" <none@nospam.com> wrote in message >> [quoted text clipped - 9 lines] >>> If there are two brake pipes, then I do not know what the problem is. >>> Sorry. The wheel speed sensor (singular, not plural) is picked up on the diff ring gear. >>>> "david" <none@nospam.com> wrote in message >>> [quoted text clipped - 12 lines] > The wheel speed sensor (singular, not plural) is picked up on the diff > ring gear. That would require both wheels to lock before the ABS kicked in. This means the brakes are out of adjustment since one brake locks and the other does not. >>>>> "david" <none@nospam.com> wrote in message >>>> [quoted text clipped - 16 lines] > means the brakes are out of adjustment since one brake locks and the > other does not. Quote from OP: > "I'm getting lockup in the rear, one or the other, or both rear wheels > tend to want to lock up when braking. " Sounds like it's not just one wheel. > That would require both wheels to lock before the ABS kicked in. This > means the brakes are out of adjustment since one brake locks and the other > does not. Gee do you think the surface the tires are on might play a role in that? I can give you a perfect adjustment, and if one wheel has less traction than the other, it is going to lock up. One tire with lower air pressure than the other is another scenario that would result in one wheel locking up. Whitelightning >> That would require both wheels to lock before the ABS kicked in. This >> means the brakes are out of adjustment since one brake locks and the >> other does not. > > Gee do you think the surface the tires are on might play a role in that? Sure, but if that was the case he would not be asking here what is wrong. Since there is a question, I'm assuming the road is flat and dry, or there would not be a question. I assume that people know that dirt on the ground can let one wheel skid before the other, therefore a complaint that one wheel skids before the other must mean the brakes need adjusting. Snow or ice can do the same thing, and I assume people know that as well. The OP is concerned that his ABS might not be working because one tire or the other seems to skid. If the truck is operated on the street, and one tire skids before the other, the ABS is not going to work and since one tire skids, the problem is that the brakes need adjusting, OR the guy needs to understand that the roadway has dirt on it allowing one tire to skid. Either way, there is nothing wrong with the ABS. Flat paved road, dry or wet. It does seem to act up more on the wet road but I was thinking this was just because the road was wet and the tires did not grip as well. Relieved to hear it's probably not the ABS system, now all I want it to do is stop like it used to for the last eight years. Del. > >> That would require both wheels to lock before the ABS kicked in. This > >> means the brakes are out of adjustment since one brake locks and the [quoted text clipped - 15 lines] > understand that the roadway has dirt on it allowing one tire to skid. Either > way, there is nothing wrong with the ABS. It sounds like your rear brakes are taking more of the load than the fronts. Just a guess, mind you ... The fronts are supposed to take (pulling numbers from the warm dark recesses of the back of my pants to illustrate the point without any attempt to be accurate enough to land an intergallatic space craft anywhere near Mars) 60% of the stopping load, and the rears then take the remaining 40%. Let's assume for a moment that you need brake service, or just had brake service that upset the perverbial apple cart, and now the front brakes are taking 55% of the load while the rears take 45%. Under such a scenario, AND having no appreciable weight in the back of your truck, it is reasonable tha tthe rear brakes would lock one or the other rear tire depending on other external factors already having been discussed. Perhaps there is air or moisture in the front brakes, or the rear brakes are adjusted a bit too tight, or the front brakes are becoming worn down or they are new but are not the same as the original brakes and thus causing an imbalance in the braking performance. If there is air or moisture in the lines, the solution is to flush the brake fluid. There are those that suggest this is routine service that ought ot be done every two years, if you have not had this service done then that is where I think I would start. Of all of the things I've listed, flushing the system is the only job that I would not do myself, mostly because it is kind of a pain in the a.s to do and I've reached the stage in my life where I have limited tolerance to crawl around under the car yelling at somebody to push the brake pedal and hold it at the bottom until I can get the screw tight again. It is not a difficult job to do, it's just a PITA. It's worth it to me to pay for this service, I do the rest of the stuff myself. In any case, your ABS is not failing you. Well, it could be failing you, but you have not described the symptoms yet ;-) > Flat paved road, dry or wet. > It does seem to act up more on the wet road but I was thinking this was [quoted text clipped - 28 lines] >> Either >> way, there is nothing wrong with the ABS. Thanks Jeff. I am leaning to what Mike H said about the e-brake cable being corroded and hanging up. When I pump my brakes in reverse and then go forward most of the lockup goes away and when it does happen, it seems to be mainly right rear lockup. Thanks for all the help, I really appreciate all the response to my question and I'm glad it's not the ABS system. I'll let you know what I find out on Sat. Del. > It sounds like your rear brakes are taking more of the load than the fronts. > Just a guess, mind you ... [quoted text clipped - 61 lines] > >> Either > >> way, there is nothing wrong with the ABS. That would certainly account for the transient nature of your problem. > Thanks Jeff. I am leaning to what Mike H said about the e-brake cable > being corroded and hanging up. [quoted text clipped - 96 lines] >> >> Either >> >> way, there is nothing wrong with the ABS. > It seems like my ABS has stopped working. I'm getting lockup in the > rear, one or the other, or both rear wheels tend to want to lock up when [quoted text clipped - 11 lines] > > PS. Please be kind, I haven't done a brake job in at least 15 years. When your wheels lock up, can you feel the ABS pulsing the brake pedal? Rear ABS is disabled when you are in 4 wheel drive. Are you in 4 wheel drive? What condition are the shoes and return springs? What condition are the wheel cylinders? > When your wheels lock up, can you feel the ABS pulsing the brake pedal? > [quoted text clipped - 3 lines] > What condition are the shoes and return springs? > What condition are the wheel cylinders? > When your wheels lock up, can you feel the ABS pulsing the brake pedal? No, just the rear lock up. > Rear ABS is disabled when you are in 4 wheel drive. Are you in 4 wheel > drive? No not in 4 wheel drive. > What condition are the shoes and return springs? The brakes were done in July. > What condition are the wheel cylinders? As far as I know they are in fine shape. That is what I'm getting looked at this coming weekend. I just do not have the time to do this myself. Del. > It seems like my ABS has stopped working. > I'm getting lockup in the rear, one or the other, or both rear wheels [quoted text clipped - 12 lines] > > PS. Please be kind, I haven't done a brake job in at least 15 years. Is this the first year you have had the truck? Does this locking up of a wheel only occur the first few stops of a trip? If so, the likely cause is condensation build up in the brake drum over night will cause the mechanism to get sticky. The first time you stop, the brakes will grab, and one or both sides will lock up. Since this is a mechanical lockup, and not a function of hydraulic pressure, the ABS can cycle the hydraulics all it wants and it won't unlock the stuck brake. Usually if it is an issue with condensation, it will clear up after the first few stops. > Is this the first year you have had the truck? No, I have had the truck for about eight years. > Does this locking up of a wheel only occur the first few stops of a trip? Yes and no, sometimes it lasts for about an hour and then just slowly clears up until I let it sit for an hour or so and then starts up again. > If so, the likely cause is condensation build up in the brake drum over night > will cause the mechanism to get sticky. The first time you stop, the > brakes will grab, and one or both sides will lock up. It does tend to do it more when the weather is damp/wet. > Since this is a mechanical lockup, and not a function of hydraulic > pressure, the ABS can cycle the hydraulics all it wants and it won't > unlock the stuck brake. Usually if it is an issue with condensation, > it will clear up after the first few stops. My problem is that it lasts more than just a few stops, if it is condensation build up, is there any way to stop the locking up? It can feel downright scary when you tap the brakes lightly and feel the rear end of the truck wanting to pass you. Someone has suggested that it make be the self adjusters getting old and sticking, is this a possibility? Thanks. Del. > Someone has suggested that it make be the self adjusters getting old and > sticking, is this a possibility? > > Thanks. > > Del. If the self adjusters where the issue you would have to opposite problem, low brake pedal and poor braking from the rear brakes. I wouldnt be too quick to rule out parking brake issue, especialy the cable going to the right side rear wheel. Thwen again it could be an issue with the brake linings themselves. I've seen cases where three linings were from one batch and the forth from a second batch causing issues like this. When it happens with disk pads you get pull one way cold, and the other way hot, sometimes quite severe. Whitelightning Thanks, I guess I wait till next weekend to see what the dealer says the problem is. Del. > If the self adjusters where the issue you would have to opposite problem, > low brake [quoted text clipped - 7 lines] > > Whitelightning ... > > Since this is a mechanical lockup, and not a function of hydraulic > > pressure, the ABS can cycle the hydraulics all it wants and it won't [quoted text clipped - 8 lines] > Someone has suggested that it make be the self adjusters getting old and > sticking, is this a possibility? ... I'm going to call it as one of two issues. #1 - Emergency brake Cable problem. If you use the cable, and it's corroded, it may hang up, causing the pads to park too close to the brake drum. #2 - Weak or broken springs in the drum causing the brake pads to sit too close to the drum. Thanks, I think you may be right. Today I started out in reverse for about 40 ft. and pumped the brake hard a few times. After doing this, it seemed to stop most of the lockup. Lockup only seemed to be on the right rear now so my vote is the e-brake cable. I'll know for sure next Sat. Del. > I'm going to call it as one of two issues. > #1 - Emergency brake Cable problem. If you use the cable, and it's > corroded, it may hang up, causing the pads to park too close to the > brake drum. > #2 - Weak or broken springs in the drum causing the brake pads to sit > too close to the drum. You just exercised the automatic adjustment mechanism. While you are looking the parking brake cable and associated parts, you should also take the tires off and look at the rear brakes and the adjusters. Between the parking brake binding and the adjusters hanging up, we have come full circle to my original guess that you had a brake adjustment issue. We've narrowed the adjustment issues to two areas. There could be more, but these are at the top of the list. The automatic adjustment is managed by a star wheel inside of the drum brakes. This wheel is at the bottom, and is situated between the two shoes. As the brakes are activated while going in Reverse, the shoes will be moved a small amount opposite of the direction they would move if going forward. This reverse action moves a lever that cranks the star wheel, which spreads the shoes and adjusts them tighter than they were before. You can have a sticky adjuster that prevents one brake from adjusting, or you could simply have no problem and just need to go in Reverse a few times and mash the brakes. Since you will have the tires off and performing a visual inspection, you can adjust the brakes manually, and this is problably better anyhow ... > Thanks, I think you may be right. > Today I started out in reverse for about 40 ft. and pumped the brake [quoted text clipped - 11 lines] >> #2 - Weak or broken springs in the drum causing the brake pads to sit >> too close to the drum. Thanks Jeff, good to know I did something right. It's all going to be looked at Saturday, wheels off etc. Del. > You just exercised the automatic adjustment mechanism. > [quoted text clipped - 35 lines] > >> #2 - Weak or broken springs in the drum causing the brake pads to sit > >> too close to the drum. This is what the dealer found: - Right side wheel cylinder leaking - contaminated shoes. - Left side badly out of adjustment. (had very hard time to remove drum) What I had them do: - Reline rear brakes. - Replace both wheel cylinders. (no sense just doing one) Total bill with tax was $473.46. It all works now, all is good. Thanks for all the responses and advice, you were all very helpful. Del. > This is what the dealer found: > [quoted text clipped - 12 lines] > > Del. Remember what I asked on Oct. 6th? > What condition are the shoes and return springs? > What condition are the wheel cylinders? and you said: >As far as I know they are in fine shape. As far as I knew they were or should have been. I had just had the brakes done in july by someone who is very reputable, new shoes, turned drums etc. This obviously happened since or was missed. I do plan on having a talk with them. Thanks for the input, it was all appreciated and yes you nailed it. Thanks again. Del. > > This is what the dealer found: > > [quoted text clipped - 21 lines] > > >As far as I know they are in fine shape. You should say nothing, and move on to a different shop. You got hosed, and they will never admit that they screwed you, much less make good. Suffer the loss and move on. Not only was it missed, it was not even looked at. > As far as I knew they were or should have been. > I had just had the brakes done in july by someone who is very reputable, [quoted text clipped - 31 lines] >> >> >As far as I know they are in fine shape.
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