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ABS light and (parking) brake issues

11K views 29 replies 4 participants last post by  noln7120 
#1 ·
I'm starting a new thread because the parking brake shoe thread was all over the place and this is a new problem.

History:
Maybe a year or two ago I knocked off a parking brake shoe while pulling of the rotors on my 2009 Hyundai Elantra. I finally got around to changing out the parking brake shoes this past Sunday. I decided to remove the wheel hub in order to get at the PB hardware somewhat easier. A hub flange bolt snapped off and was a major PITA to remove. Fast forward to today...

I replaced the parking brake hardware this afternoon. Afterwards, I mounted the wheel hub and torqued down the 4 bolts to about 44 foot lbs (source I have says 43-50). I noticed that the rotor went on rather snugly over the PB shoes. The star wheel was totally bottomed out, so there was no more room for adjustment. I loosened up the adjusting nut by the parking brake handle and that seemed to help things a little (or maybe it was my imagination). I then went for a test drive.

At first there was a nasty grinding noise and pulsating in the pedal, which seemed to go away after I pulled up on the PB lever a few times while going slowly. The brakes then operated fine afterwards. The PB had no real bite though and wouldn't even hold the car still when it was in drive. So I decided to tighten the adjustment nut again to see if I could get the PB working better. On the next test drive, there was a grinding noise again. This time the ABS light came on (it might've come on earlier during the 1st test drive but may not have noticed).

So, when I start up the car (has happened 4-5 times since the 2nd test drive), the ABS light comes on. Once I get going, the ABS light goes off. The brakes also make noise at this point while the light is off. Pulsing and a nasty noise. After a minute, the ABS light comes on then the brakes operate fine. No noise, and no pulse - just the annoying yellow light.

Can an improperly adjusted e-brake cause the ABS light to come on? Would it cause pulsing in the pedal and noise? The noise sounds like it's coming from up front, which is weird.

One other thing to mention... while removing the stuck bolt from the wheel hub, there was a LOT of heat involved. I noticed the tone ring had gotten warped ever so slightly from the prolonged heat. Can this be affecting the ABS light? I don't feel any vibration from the hub while driving. It feels like it did prior to me messing with everything. I had the rear of the car jacked up for 3 days straight.

I'm at my wit's end with these 3 days of going nuts with the car, no results, and messing things up even more. Any help would be much appreciated! Sorry for the novel...
 
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#2 ·
Would it cause pulsing in the pedal and noise? The noise sounds like it's coming from up front, which is weird.
My guess is the noise your hearing and the pulsing pedal are being caused by the ABS operating...which is under the hood.

noln7120 said:
One other thing to mention... while removing the stuck bolt from the wheel hub, there was a LOT of heat involved. I noticed the tone ring had gotten warped ever so slightly from the prolonged heat
And that is probably what is causing it...rotor deformation (the rotor in this case being the tone wheel). Basically, the speed that the ABS module is seeing from that wheel doesn't match the other 3 (due to the damaged tone wheel) and the ABS is trying to correct the problem by rapidly releasing and re-applying the pressure to that brake. It's something we more often see when one of the tone wheels split due to corrosion.
 
#3 ·
I do not think ABS is trying to apply pressure, because if it did, it would stop the car. ABS cannot apply partial pressure. It goes full or nothing to each wheel separately.

Now, the problem you got might be the sensor which is in the rear wheel you worked on. Check if you moved it by any chance or maybe got partially disconnected.

Now, to PB. To properly adjust it - remove wheels on both sides, loosen the PB lever, check if wheels rotate freely. Pull the lever to the 1st tooth. Leave it there. Using the adjusting screws in the drum, unwind them until the pads start pulling. Do about the same force for both sides.
The tricky part - to properly seat them you must turn the wheel BACKWARDS. This engages the locking mechanism and seats the shoes.
So, after being done with initial adjustment, pull the lever hard, then back to zero, check for any dragging, pull the 1st, no dragging should be there, maybe a tiny bit, pull 2nd, you should not be able to rotate any wheel. Then back to 1st and backwards rotation with hands. If cannot, put the wheel on and try, or use a breaker bar, but protect studs with lug nuts.

Once assembled, get into the car and drive in reverse and pull the hand brake gently until it locks.
All set.


As for ABS again.
I do not recall what is the mechanism on this one. If the sensor looks on the outer or inner part of the rotor. I am just sure the sensor must have been moved out of place or covered with some dirt.
Compare other side for reference.
ABS sensor is simply speed sensor... and it is magnetic, not optic.


Pulsating pedal.
That must be related to pads. Is the foot brake working fine? Are the pads seated properly? Any binding when in air? Can you freely spin each wheel by hand?
If not - check.
Also, sometimes hard brake application helps to get them seated.
 
#4 ·
It's possible I got some anti-seize on the sensor because I was quite liberal with the application. I put it on the 4 bolts and on parts of the hub. Maybe some got transferred to the speed sensor.

As far as the questions relating to the pads - I had zero problems with my brakes before messing with the rear wheel. The brakes work fine (besides the ABS light on) shortly after starting the car. Here's the exact process:

Right after I start the car, the ABS light comes on. As soon as I start driving, it shuts off. Then there is noise when I'm braking (grinding) or not (clicking). I also thought I heard some mechanical whirring from up front. The pedal also pulsates. After maybe a minute or two of this, the ABS light comes back on and the all those symptoms disappear and the brakes appear to be totally fine except for the ABS light being on.

All the pads have been seated properly. I didn't check for any binding from the front pads because those gave me no trouble in the past. I did check the rear wheels as I was adjusting the parking brake and each wheel would spin a few times and then stop. The side I worked on (with the new PB shoes) seemed to have a little more resistance than the other side.

That parking brake adjustment sounds like a b**ch!

At this point, I'm thinking my issues stem from a combination of the following: 1) Slightly warped tone ring 2) speed sensor being dirty or busted somehow during the hub removal process 3) improperly adjusted parking brake.

I'm going to order a Timken wheel hub from Rock Auto and attempt to replace it on Monday (which is hopefully when the hub will arrive). I figure I'll start there, inspect the sensor while doing the hub, and try to readjust the PB afterwards.

If all else fails I'll just bite the bullet and take it to a mechanic.
 
#6 ·
Get the parking brake done. It is a quite process, but once done properly you will be happy.
I hope no grease got onto the shoes.

ABS, like @AUTOSPARK ; mentioned - it shuts down.
What you hear in the front is the pump that is confused.
I bet if you were to slam the brakes, it would simply lock wheels.
As it may seem OK, ABS is responsible for brake force distribution. Hence, your rear may be either too weak or too strong at some point.

Do you have TC/ESC on it?

Check the sensor. Just know one thing - even if you correct it, the light and noise may be back after the first startup. You may need to drive it a bit (faster than 20 mph) for it to "learn" all is OK.
 
#11 ·
visual inspection. testing is not easy, unless you can use multimeter and only measure resistance of the unplugged sensor.
What it should read? I am not sure... but anything like 5 Ohm or below is not good or anything like MOhm is not good.


As for the tone wheel.
I would not go this route yet. Even if it was damaged (I mean how damaged? All teeth rubber off? Completely gone? The sensor/system allows for some "play". The ring does not have to be perfect...
Besides, if ABS complains from the moment you start, there is something else going on even before the car is in motion.

I would start with this what you can inspect and check/fix before ordering new parts.
Do not jump to conclusion too early.

It could easily be ABS unit that went bad because you damaged sensor and shorted a circuit... but why would you buy all parts before confirming?

I agree, tone ring is crucial, but many times they are rusty, dirty, and still work fine. Warped - it would have to be off by several mm, even a cm to cause a problem.
 
#12 ·
testing is not easy, unless you can use multimeter and only measure resistance of the unplugged sensor.
Resistance measurement isn't recommended for modern active wheel speed sensors. Active sensors contain a semiconductor device and if the ohmmeter is connected the wrong way round the reverse voltage can damage the sensor.

2009GLS said:
What it should read? I am not sure... but anything like 5 Ohm or below is not good or anything like MOhm is not good.
If you did take a resistance measurement on an active type sensor the resistance would likely be in the MOhm range. MOhms is good on modern sensors.
 
#13 ·
Great advice guys, I really appreciate it.
@2009GLS - the part is ordered now so in the worst case scenario, if I don't need it (and the sensor turns out to be the issue), I'll just send the hub back for a refund. But I totally get what you're saying.

Two major noob moments I wish I could have back:

1) Taking the darn hub off to change the parking brake hardware. It was totally unnecessary and has put me in the predicament that I'm in now. I've never toyed with wheel hubs or e-brakes before. I've only attempted drum brakes twice (messing up the first time, success the 2nd time). I'll just chalk it up to "you live and you learn."

2) I think I should've just swapped out the hub for a new one when I had the part finally off the car. The hub was rusty, had 75k miles on it, and had a broken bolt that still needed to be removed. I have a feeling that the ultimate issue here is the hub/tone ring (and not the sensor) and if I just would've replaced it off the bat, everything would be good right now except for still needing to adjust the e-brake. We shall see, I guess.

On Friday, I plan on inspecting the wheel sensor to make sure it's not dirty, banged up, knocked out of place, etc. If toying with the sensor doesn't fix it, then on Monday or Wednesday, the hub should be here and I'll swap it out, cross my fingers, say 10 Hail Mary's, and go for a test drive. If it's still not fixed at that point, then off to the mechanic I go. I'll update this thread when I have more info. Thanks again!
 
#14 ·
What you describe could very likely be an issue with the tone ring, not the sensor or the abs unit. The pickup is very sensitive and slight deviations in the signal can cause a fault - that can be dirt, chip, warpage or other mis-alignment of the tone ring. All you are experiencing is a fault in the ABS unit - a stored code that prompts the system to do a self test - then it shuts down after failing the test and remains shut down until your next startup cycle.
 
#16 ·
it's a very basic hall effect sensor at least on my daughter's 2007, but that car lacks esp - it's a magnet surrounding by coil of wire which generates a low voltage signal. No harm in doing a continuity test.
 
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#17 ·
2009GLS said:
Modern like today or in 2005 when they designed HD Elantra?
Modern like the turn of the century.

dtech said:
it's a magnet surrounding by coil of wire which generates a low voltage signal.
There are no coils of wire inside a active sensors, and they don't output a voltage. At least, none of the ones I've had any dealings with do. They do have a type of hall sensor element inside though.

They work by altering the current flow in the circuit. That's why you need the series 75Ohm resistor to test them. The current flowing through the resistor creates a voltage drop across it that can be measured by the scope.

dtech said:
No harm in doing a continuity test.
It might not do any harm but it's not really a valid test for this type of sensor. It wouldn't show any continuity anyway because the resistance is so high, and the manufacturers don't publish resistance values for them. So if you did measure the resistance you wouldn't know if the measured value was correct or not. I suppose you could compare it to a known good sensor but like I said, it's not really a valid test.
 
#18 ·
It's been maybe 5 yrs since I replaced the sensor on the 2007 Elantra but I thought it was 2 wires - which usually is a passive sensor, but could be mistaken. I recall spinning the wheel failed to generate any detectable current flow.

I think the OP has come to right conclusion as those sensors are pretty sensitive, even more so if it's an active sensor design.
 
#19 ·
Pretty sure it's a 2 wire sensor as well. I recall seeing a pic of the connector and only seeing two slots/posts on the inside.

Can anyone explain in the simplest of terms how to check the output voltage of the sensor with a basic multi-meter for someone who is electronically challenged? I'm having trouble making sense of the thumbnail I attached on the last post of the last page.

Here's how I interpret that picture (don't laugh):

Disconnect the sensor from the wire harness. Run a wire from one prong of the wire harness to one prong on the sensor, essentially leaving half of the connection connected. This represents the "Vin" connecting the "Power DC 12V" to the wheel sensor.

For the "Vout", a wire would run from the other prong on the wheel sensor to the resistor. One of the clips from the multi-meter would be connected to this same end of the resistor. The other clip from the multi-meter would be connected to the other end of the resistor. Then a wire would also run from one end of the resistor to a ground on the car.

Does this sound correct? Again, I apologize when it comes to the electrical stuff and my interpretation of it. Definitely weak in that department lol. I attached the diagram to this post as well to make it easier to compare my interpretation of it to the actual diagram.

Last, but not least, is there a way to check the sensor without having the 75 ohm resistor? Thanks!
 

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#21 ·
Found this link to some additional info regards fault modes. Now I'm recalling that maybe my diagnotics for replacing the right front sensor on my daughter's 2007 was based on the steering assist also flaking out and reading that sensor also provides input to steering assist. I see harbor freight advertises a OBD II and ABS code scanner for $100 .


AutoHex Online Help: Hyundai ELANTRA(HD) 2007 Fault Code: c1200
 
#24 ·
Success! The ABS light was being caused by the wheel hub. Here was the process that I followed today:

First, I took off the wheel and rotor. I located the sensor and took off the one bolt. I tried prying on it with a screwdriver but the thing wouldn't budge. I then removed the hub, and sure enough, I had slathered anti-seize all over the sensor. After wiping it off, I was determined to get the sensor out. I started spraying it with PB blaster and waited a little bit. More prying, no movement. I then tried to take a small piece of wood and pound it out from the inside. Still, no movement. Tried prying once again, and got the slightest bit of movement. Then I took some channel locks and gripped the very base of the sensor wire by this little plastic shroud and started twisting. I was able to slowly work it free that way. Took maybe 30-45 mins to get the thing out and was a major PITA. Cleaned it off and then tightened it back down.

At this point, I wanted to see if the issue was caused by the sensor so I decided to extend my work day and reassemble everything and go for a ride. I could've just slapped the hub on which would've been much quicker, but then I wouldn't have pinpointed the cause. Upon starting the car, the ABS light was off (it was usually on). Had some gritty braking at my first stop and then light lit back up. Back to work.

Jacked the car back up and this time replaced the hub with the Timken part I had ordered. Reassembled everything, went for a ride, and no light and no funky braking:) H*ll yeah! Here's a pic of the old hub which shows the the tone ring and what caused the ABS light.



Had about an hour of daylight and then tried to adjust the parking brake. It works, but rather badly I think. I need to go back to the drawing board with that one. When I replaced the PB shoes, I only replaced them on the side where the shoe had fallen off. Tomorrow I'm going to replace them on the other side. Maybe that will even things out a bit because I feel like the driver side (which I didn't change the shoes on) is doing all the work.

When I look at the hand brake lever adjustment, both cables are not even (think the driver side rides up a lot more) when I pull the lever up. Is it supposed to be?

I have the passenger side star adjuster bottomed out because when I turn the wheel, I get one complete revolution of the wheel when spinning it. If I spread out the adjuster at all, the wheel doesn't want to move. On the driver side, it goes from spinning pretty freely (2 full revolutions) to locking up the rotor with maybe one click of the adjuster.
 
#25 ·
Success! The ABS light was being caused by the wheel hub.
What, it was the damaged tone wheel that was causing all that pedal pulsing and noise....I'd never have guessed :laugh:

Anyway, great to hear you got the ABS side of things fixed. Now onto the parking brake adjustment, which I always find a PITA on Hyundai too. Sorry, I can't offer any advise on the best way to do that. I'm hopeless with mechanical things.
 
#27 ·
The tone ring was damaged from excess heat while trying to remove the bolt with the snapped off head that was stuck. At that point it was removed and in a vise. You would think that the bolt would come out of there easy with that kind of access, but no, it was still really, really difficult. The guy who helped me with it told me he's removed hundreds of broken bolts before, and the one on the hub was one of the hardest ones he had ever tackled.

Thanks guys!:grin2:
 
#28 ·
So I worked on the parking brake today and had decent results. It's good enough for now. One question though - without the parking brake on, if I have the rear end jacked up with the tires on, how many revolutions should they spin if I give them a decent push?
 
#29 ·
With the wheel on or off?
You see, it is very subjective. It depends how good bearing you have, what grease you used, and how warm it is. Not to mention brake dragging.

The best way to tell is to pry out the pads (insert flat screw driver and pry them outside) and then spin. It will tell you if the shoes drag at all. If they do - you know what to do. You will hear them dragging. As for resistance - again, no definite answer as your decent push may be strong for me, or weak... :)

Strap a 100 g weight to top of the wheel. Turn it a bit to one side and see where it ends after stopping. Is it the bottom? All good. Did it stop like 30 degrees off the center line counting from the bottom - well, a bit of a resistance. Would it stop 45 degrees - something is very wrong.
 
#30 ·
I was thinking with the wheel on. When I go to work on the timing belt next, I'll inspect the PB one more time and try what you said with prying the pads away.

When it came to adjusting the PB, I have it set at about 8 clicks (it was at about 14 lol) but the resistance doesn't really start kicking in until the 4th or 5th click. At 7 or 8 clicks, it will hold the car in place while it is in drive. The two lines by the adjusting nut now sit even with each other after I changed out he hardware on the driver side. I was having a difficult time getting good resistance on an early click (like the 2nd) without thinking that the shoes were binding up the rotor to some degree.

I don't like to think about it, but I turned a 4-5 hour job into a 35 hour job by removing that darn hub. Ugh
 
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