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ABS Brake Questions and Answers
This category contains featured questions as examples. They relate to most vehicles.
Question: 1998 Ford Explorer mileage: 137,000. I am having a problem with the ABS system. Just before I come to a complete stop I feel the brakes pushing back and making a hissing sound. I'm not having any issues stopping at all. This morning the brakes didn't push back but the ABS light came on. Now the ABS light is off again and the brake is pushing back again. I've been told it's many issues from a bad sensor to air in the brakes.
Answer: Scan the PCM (Powertrain Control Module) for fault codes in the brake system but it sounds like you have a wheel sensor that is malfunctioning.
Question: 2002 Chevy Astro ABS 4.3_mileage: 99,000. My Van with ABS has had brake problems for two years and over the course of these two years I've had two complete brake jobs, new Calibers on the front, had the drums and disc turned, bleed the brakes and....the problem is: whenever you perform any of these mention things to the brake the brakes would work fine...then 2-4 months later...the brakes would become very touchy whenever you step on the brake pedal at a slow speed. And...it would just about put you though the windshield until I get the brakes bleed or get a brake job etc. Can you please help? The Chevy dealer doesn't know what would cause this problem so they are recommending a complete replacement of the brake system for $1500.00. I am sure it has got to be something simple.
Answer: Replacing the rear brake drums and brake shoes with brand new parts from the dealer or eAutoPartstore.com...not relined brake shoes...should solve your problem. Not all relined brake shoes are created equal.
Question: 1999 Toyota Camry 4 cyl_mileage: 75,000. The ABS light stays on. Toyota told us it would cost about $1800 to repair. Since the car is driven only by me - and not used a lot, I would like to skip the repair. The car runs beautifully and the brakes work fine without the ABS. However, we were told we could not pass inspection with the ABS light on. Can we just disconnect the ABS without computer problems? Might the cost be less than $1800 for repair? I learned more about my Camry reading all your other questions and answers. I learned that Camry\'s have a lot of miles in them. We have maintained this car since the first day we bought it - could never get its worth in a sale or trade in. But $1800 is a lot of money for something we don't seem to need.
Answer: We suggest that you get a second opinion from an independent service source. You may find that something as simple as a wheel sensor has failed which would be relatively inexpensive to repair. Question, did the Toyota dealer tell what art of the ABS system failed? Some parts are very expensive. We would never suggest that you disable the ABS system...the system was designed to give you an extra margin of safety while braking.
Question: 2001 Chevy Blazer 4.3 Vortec 4x4 _mileage: 92,000. The trouble I am having is with the braking system, the brake pedal goes to the floor when you step on the brake. To solve this problem I have replace front and rear brakes and the master cylinder I have checked the pin in the vacuum booster and bleed all the lines figuring the job was done. The brake pedal is firm when not starting vehicle, but when the vehicle is running it again goes to the floor. I am thinking of replacing the ABS unit. All lines going to the unit seem to be operable but I am not sure. There is no fluid coming out of the bleeder screws in the top of the unit. I know the abs wheel sensors are not working but I just had this vehicle certified like that in late November and all brakes were working fine at that time. They don't seem to be locking up properly when on a test drive. Maybe you can give me a suggestion. Thanks! Answer: Sounds like you still have air in the brake system which power bleeding will probably correct. Check the rear wheel cylinders as they may be letting air into the system when the parking brake is applied.
Question: 1999 BMW 750il 4000 mileage: 83,000. Hi, I'm the unfortunate owner of a BMW with an ABS problem. On starting the engine the ABS carries out its usual test and both the traction control and ABS lights go out. As the vehicle accelerates away and reaches above 5mph, both lights immediately illuminate and stay on. The fault can sometimes be cleared by switching off the engine, restarting the engine and then counting to 30 before engaging reverse, then reverse the car with full left hand lock on the steering wheel! The car will then drive away normally without either of the ABS lights illuminating. If however either of the rear wheels are spun, i.e. on gravel, then both lights will immediately illuminate and stay on. The car has been into the local BMW dealership for diagnostic checking, where they informed me that the pump relay was faulty. This has been replaced to no avail (and also the memory reset). They are now talking of requiring to test the car further for up to a day, at �85 per hour, just to find the fault! Prior to sending in the car initially, I removed all four wheel sensors and checked each of their resistances, which were all comparable. Although one on the left rear was found slightly bent due to stone damage, it was easily straightened. All four wheel segment rings were also cleaned up and in good condition. Any positive advice of tests that I could carry out would be greatly appreciated, before breaking the bank. Thanks in anticipation.Answer: Your problem probably lies in one of the four wheel sensors for the ABS. There is a better test than the resistance check you tried. Unplug each of the wheel sensors. Spin the wheel segment rings and check for AC voltage at the sensors. You should have between 1 to 3 volts AC if the system is operating properly. Also check to see if you have a slightly loose wheel bearing that is allowing the segment ring to contact the wheel sensor.
Question: 2003 Chevy Suburban mileage: 67,000. I'm having problems with the antilock brakes. My mechanic has tested the system. The brake system activates just before coming to a stop. The system has three sensors. The front sensors read zero below 8 miles per hour. The back sensor reads right to zero. They have called GM and have not got a response. The truck is almost not drivable in bad weather (snow). The pads are good and the shoes are too. The rotors were replaced at around 70,000 miles. The truck is 4 wheel drive. The front sensors are in the wheel bearing assembly.
Answer: It sounds like you have a bad front ABS sensor. Check the output with a volt meter. Replace as needed recheck systems.
Question: 1999 Ford E150: One year ago last month my conversion van had the antilock brake light come on and then my rear brakes locked up. I took my van in for repair. I told a local repair shop my trouble and they said they thought the problem was in some junction block in the front of the vehicle but said I would have to take it to a dealer because of the antilock problem. I took it to the dealer and they began replacing all the parts on my brakes such as new front brake pads, calipers, lines, rear brake drums, wheel cylinders, master cylinder and so on. This over a period of a year telling me nothing was wrong with the antilock system. Meanwhile the ABS light has always stayed on and the rear brakes continue to lock up. The van has now been in the shop for two weeks and they can't seem to find the problem. Do you have any ideas? I am getting desperate and broke by each repair.Answer: We have repaired vehicles with similar problems by replacing the rear brake shoes with brand new, not relined, purchased from the dealer. Also, replace all the rear brake hardware, springs, etc.
Question: 1999 Chevrolet Cavalier mileage 110,000 When driving slowly on snow or even a wet road, when I hit the brakes relatively hard the back brakes lock up and the ABS kicks in. When this happens I seem to loose braking ability in the front (and have almost caused a couple of accidents where the person in front of me could stop faster on wet pavement). It's seems to me that when the ABS kicks in at the back it also lets off or stops applying more pressure to the fronts, even if I stomp on the brakes harder. I can actually bring the car to a stop much faster by just pushing the pedal to the point where the backs almost lock up; but this is not efficient because the fronts are not used to their full potential. It has happened ever since I got my front rotors and pads changed and the backs only cleaned and adjusted. Is it the difference in brake material from front to back that would cause the back brakes to be applied much harder? Or is it a pressure problem, too much is sent to the back? Or is it an ABS problem? Even on dry pavement I do notice the car seems to be braking quite hard from the back (which is better than before I had the brake job when the backs weren't catching at all). What do you suggest, replace back pads?
Answer: Based on the information you sent to us, what we believe may be happening is the rear brakes are improperly adjusted and the front brake material may be too hard. Therefore, we would recommend replacing the front brakes with General Motors pads designed for your car and make sure the rear brakes are properly adjusted.
Question: 1998 Chevrolet Tahoe mileage: 88,200. About a month ago when coming to a stop from a slow speed, it feels as though the ABS kicks in. Six months ago I had the same problem and the mechanic replaced the rear speed sensor, left front hub and bearing assembly and the right rear emergency cable. That was about $800. Could the same thing be happening again after six months and 7,000 miles?
Answer: We have worked on Chevy trucks with symptoms similar to yours. Replacing the rear brake shoes with brand new brake shoes purchased from the dealer fixed the problem
Question: 1992 Chevy Astro AWD 4.3 mileage: 125,000. We have a severe pull to the left side when braking. We have checked the pads and rotors, changed the calipers, and new shocks. We jumped the ABS system and found that it needed a new micro-valve (costing $900) so instead of buying we wanted to make sure that was the problem and by-passed the ABS system by going from the master cylinder to the breaks. This still did not solve the problem of the very aggressive pull to the left when breaking. We have looked at the sway bar, looked ok, but we are not sure about the torsion bar that goes towards the rear of the vehicle. We are looking for ideas of what would cause this pulling to the left. While driving it, drive straight down the road with no noise. Once the brakes are applied, the vehicle will seem to straighten back up but by that time, you are in the opposite lane ready to be hit by an oncoming car.Answer: Your problem may not be in the brakes. More likely it is in the suspension. Check for worn, bent or broken components; ball joints, control arms, etc. In addition, check the rear suspension.
Question: 1999 Chevy Tahoe Vor-350, mileage: 36,123. I bought this Tahoe new in '99 and after about 12,000 miles, we experienced pulsating front rotors. The dealership replaced them only to have to do it again at 22,000 and again at 33,300. We do not tow anything and drive normally. Now the Warranty is out and I am faced with having to do it again. We have tried changing wheels and hardware. When it starts it doesn't take long to get really bad, maybe 1000 miles and it shakes so badly it wants to break traction on the front tires (at a Hard Stop). Very annoying!
Answer: In order to answer your question we will assume the dealer replaced your rotors with new ones (not your old rotors re-machined), that you do not have oversized tires and non-stock wheels and the lug nuts were properly torqued to specification with the correct tightening pattern. Now, check to see if the front brake calipers might be hanging up slightly during the time you are driving, causing excessive heat on the rotors. In addition, check to see that the rear brakes are functioning properly so as not to overload the front brakes.
Question: 1998 Chevy 2-wd 1500 350tbi mileage: 106,000. Hey guys, I have a new motor, complete new pads, wheel cylinders, master cylinder, and I can't get a pedal, tried everything! My brakes don't work.
Answer: Sounds like you have air in the brake system. Try removing the master cylinder, "bench bleeding" it and then reinstall it and bleed the entire system. If the low pedal still persists, try replacing the rear anti-lock brake valve.
Question: 1999 Mercury Grand Marquis 4.6L mileage: 124,000 ABS system activates below 70km/45mph with no warning lights and no error codes. Dealer could find no problem with sensors or sensor rings. Ford TSB says to check for poor or corroded connections which dealer says can take several hours of trial and error to track down. I know that one or both of the front rotors is warped, could this cause one of the sensors to give a false output at lower speeds? I am not convinced about the poor connection theory as that usually leads to erratic or sporadic problems and this problem seems to be speed related.
Answer: You may have a faulty ABS computer. We would obtain a known good computer and substitute it for the one in the car first to eliminate the computer factor. If the computer proves not to be the problem, the connectors would need to be checked for corrosion or high resistance. Warped routers would not cause the problem you described.
Question: 1999 Plymouth Neon mileage: 75,000. This is a brake-related question. I recently noticed that both front rims seem to heat up under normal driving conditions. I've had the front caliper assemblies professionally replaced, which has reduced, but not eliminated, the heating. I guess my question would be this: Is it normal for front disc brakes to heat up enough to make the rims almost too hot to touch ? (There are no noticeable signs of a pad dragging or anything of that nature--and it does seem to occur equally on both sides.)
Answer: During normal driving the brakes and wheels do get hot. Make sure that your brakes are not dragging. If you have aftermarket rims, they may be blocking the air-flow which keep the brakes from cooling properly.
Question: Hi my name is Ryan and I am doing a school project. Will you tell me why disc brakes have replaced drum brakes? Thanks.
Answer: Disc brakes are much safer than drum brakes. When drum brakes get wet, as when it rains, they do not stop a vehicle at a safe distance. Moreover, if only one of the front brakes gets wet, the vehicle will swerve dangerously to one side when the brakes are applied. With disc brakes, the vehicle will only veer slightly.
Question: 1999 Chevrolet Tahoe, AWD 1997. Eng. 5.7 liters. ABS Kelsey-Hayes 4WAL. During deceleration when the car reaches 6 mph both front sensor values drop to zero at the same time and ABS activated (Brake pedal pulses and deceleration become wrong). During acceleration, the rear sensor works well but both front sensors value zero. When the car reaches 6 mph, both front sensors value OK. (Same as rear and remains the same during the trip). We checked the resistance of the sensors and we find 1050 ohm for both. Unfortunately, we have documentation for older Tahoe's only. In these documentations, we find that the resistance of the front sensors should be around 2.5 - 3.0 k ohms for AWD and around 1.0 k ohms for RWD vehicles. We checked P/N of the sensor and it was OK. We ordered new ones but the resistance of the new sensors were 1.0 k ohms so we doesn't fit them. Have you any idea to solve this problem? Charlie, Budapest
Answer: Check the front brake rotors. There should be a reluctor that is part of the rotor that the sensor reads. If the brake rotors have been replaced in the past, there is a chance that the wrong ones were installed without the reluctor. Also, check the voltage generated by the sensor when the rotor is turned at low speeds. The voltage will be AC current, not DC current. At low speeds you should get somewhere between 1 and 5 volts.
Question: 1999 Ford Thunderbird mileage: 124,000. The brake pedal slowly went to the floor with the engine on. Replaced master cylinder in November 2000. Drove it yesterday (my daughter has it at college) found that, sitting at a long stop sign, if I pressed harder, the pedal went to the floor. Didn't seem to lose braking power though. Is the replaced rebuilt master cylinder bad? Could it be the booster? She says, though I haven't tested, that the pedal stays up with the motor off, seems I recall that is how it behaved last November. Bled the whole system then, found a hard pedal with the motor off. Now it makes me think booster, though how can the pedal go to the floor if it goes directly to the master cylinder? PS, checked the archive, and the jeep with the pedal to floor problem sounds just like this, but guys, it has a rebuilt unit in only since November.Answer: It probably is your rebuilt master cylinder. We have not had much success using rebuilt master cylinders.
Question: 1999 Ford F150 4x4 302 mileage: 102,000. When I apply the brakes my truck pulls really hard to left, as if the right caliper is not grabbing very good. I have just recently replaced the right brake caliper and put new pads on both sides. We even thought maybe the new caliper we put on was defective so we pulled it and replace it again. Still pulls hard to the left when braking. We have bled both sides several times and there is no air in the lines. The left caliper was replaced about 2 years ago but the left side seems to be working. The right side doesn't feel like its grabbing, or the left side is grabbing to much. We are stumped and so is everyone else I ask. Do you have any ideas?
Answer: It is normally a good practice when replacing brake calipers to replace both of them. Check for worn or loose suspension components and check brake rotors to see that they are not machined undersized. Check to see that the slides on the calipers are working free and not binding.
Question: 1999 Ford Thunderbird SC 3.8L SC mileage: 145,000. My '89 Thunderbird super coupe has all wheel disc ABS. The motor to the actuator is not charging. The wires to the motor are only showing a half a volt when I tested them. In fact, all of the wires I checked to the ABS under the hood only had about a half volt. Someone drained the brake fluid completely and then filled it up. That's when they said the problem started. I read in a book that if the pressure switched is replaced then you must replace the pump motor relay. Maybe the loss of fluid caused that pressure switch to go bad which popped the relay. Well the moral of the story is where could the pump motor relay be? The dealer wire diagram says on "RH of dash on relay bracket" along with the ABS modular relay. I can't find this. All I found was the brain to the car. The computer to the ABS control in the trunk has power (forgot to tell you that). If you can help me locate this relay or know what the problem is I would greatly appreciate it.Answer: The relay is located on the firewall on the passenger side. Be prepared, you may have to replace the entire ABS unit to get proper function.
Question: 1995 Ford Thunderbird V-8 4.6 mileage: 63,000. My emergency brake is hanging down underneath my car. How do I tighten it? When the brake is on it does not hang down. When released it sags underneath my car.
Answer: Check for clips on the underneath side of the car that hold the cable up. They may have been inadvertently knocked off. Also check the return springs on the rear brakes to see that they pull the cable back when the parking brake is released.
Question: 1998 Eddie Bauer Ford Bronco 2 mileage: 177,000. I have a habit of putting on the parking brake each night when I leave my car because my driveway is on a minor slant and I feel this is the safest option. This morning, when I removed the brake...it felt as if the brake was somewhat still on. Not fully, more like 50%. I have a short drive to work, about a mile and a half, so I risked it. When I got to work, the rear tire well smelled like burned rubber. What's wrong!
Answer: Sounds like your parking brake is not fully releasing. Have the rear brake drums removed and have the return springs checked.
Question: 1998 Chevy Lumina 3.1 mileage: 100,200. I had my disc brakes pads replaced in Jan of 2000. They are bad again after 15,000 miles, which were mostly highway miles. I have an unlimited guarantee on the pads and labor for as long as I own the vehicle. I called the shop and the mechanic told me he believes the calipers are sticking. The mechanic told me he wants to rebuild the calipers. My question is does this sound logical for the caliper to freeze up without any kind of warning or signs other then the brake pads wearing out?
Answer: It is very difficult to diagnose your problem from without seeing your car. However, we would suggest that you have the brake calipers checked by a mechanic other than were you had the brake job done. Check with friends and neighbors for recommendations.
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