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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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