# Stabilitrack and ABS lights on, service bulletin



## Gilly (Sep 11, 2012)

Thought I'd share, my wifes car suddenly had a stabilitrak and abs lights coming on. Took it in and they looked at it the next day, they gave me a loaner .
Said there is a bulletin on the problem, involving the "magnet", I assume they mean the sensor, which is magnetic, accumulating metal shavings. Unsure where they shavings or metal is from. And this they said was on the left rear (I think our Cruze has rear drum brakes?). It would be in the hub area. Anyways they had a code for this problem and they cleaned off the "magnet" and the lights haven't come back. She said there were no driveablity concerns, just the lights coming on.
Gilly


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## iCruze2 (Dec 16, 2011)

Mine has the same issue but add service traction control as well. I'm going to make an appointment for Tuesday morning.


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## Jim Frye (Mar 16, 2011)

This is an old problem. It was written up in Techlink back in late '11 or early '12. The speed sensors on each wheel are composed of a ring of magnets in each hub and the sensor reads the magnetic pulses to determine wheel speed. If dirt gets on the ring, the pulses can be misread. The dealers should be able to fix it as it is well documented for them.


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## Gilly (Sep 11, 2012)

Well I would hope it's not dirt, I hate to think of taking this in every 6 months for "oil change, rotate tires, and clean the wheel speed sensors".


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## Chevy Customer Care (Oct 29, 2011)

Gilly said:


> Thought I'd share, my wifes car suddenly had a stabilitrak and abs lights coming on. Took it in and they looked at it the next day, they gave me a loaner .
> Said there is a bulletin on the problem, involving the "magnet", I assume they mean the sensor, which is magnetic, accumulating metal shavings. Unsure where they shavings or metal is from. And this they said was on the left rear (I think our Cruze has rear drum brakes?). It would be in the hub area. Anyways they had a code for this problem and they cleaned off the "magnet" and the lights haven't come back. She said there were no driveablity concerns, just the lights coming on.
> Gilly



Gilly,
Thank you for sharing this. I am happy to hear that your dealer was able to get this taken care of for you. If you have any other questions please feel free to contact me anytime.
Thank you,
Stacy Chevrolet Customer Service


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## Chevy Customer Care (Oct 29, 2011)

iCruze2 said:


> Mine has the same issue but add service traction control as well. I'm going to make an appointment for Tuesday morning.



iCruze2,
I am sorry to hear that you are having this issue with your Cruze. I would like you to keep me posted on your service appointment. If you have any questions please feel free to contact me anytime.
Thank you,
Stacy Chevrolet Customer Service


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## Robby (Mar 1, 2013)

Each wheel bearing has a speed sensor built into it.
The sensor is a electromagnet and it is stationary.
On the hub side of the bearing, there is a ring with, what a novice would call, teeth.....like a gear.
The two components are the speed sensor.
The electromagnet is powered whenever the vehicle is running and, when in motion, the trigger wheel (gear) turns with the vehicle wheel.....as each 'tooth' passes the electromagnet, a return signal variation, due to the proximity of each tooth passing the magnet, is sent the the ABS computer.
As long as wheel speeds are the same, plus or minus a pre-established range, the computer is satisfied that it is sending a signal and recieving a signal.

All that gobblygook to say that the metallic brake dust is attracted to the electromagnet.......and sometimes too much of it accumulates.
This interferes with the signal and is what sets the ABS/TRACTION CONTROL lamp.....the computer is getting flawed information.

All vehicles have the potental for this concern, but as a percentage, few are ever affected by it.
Usually any accumulated metallic particles drop off when the ignition is turned off.....but, as can be seen, sometimes a bit hangs in there.

Really nothing the consumer can do to avoid it.

Usually, simple cleaning and compressed air blow-off of the electro magnet (known as a stator btw) resolves the issue.

Rob


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## iCruze2 (Dec 16, 2011)

So it's a fast fix? I won't need a rental?


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## Lostiguy (Feb 15, 2014)

Sorry to have to resurrect this thread but I just started having this issue. 2012 2lt with 48000,Stabilitrac and Antilock light stay on. Has anyone tried to clean the wheel sensors themselves? Searched for a how to but couldn't find anything. Thanks


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## Chevy Customer Care (Oct 29, 2011)

Hey there Lostguy,

I'm sorry to hear that your Stabiltrac and Antilock light stays on. I will be glad to look further into this concern that you are experiencing. Please feel free to send us a private message with your VIN, current mileage, dealership name, and full contact information if any extra assistance is needed. I look forward to hearing from you soon!

Kristen A. 
Chevrolet Customer Care


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## Robby (Mar 1, 2013)

Well.....my old post about cleaning is not revelent to the newer design hub assembly found on the Cruze and most other late design assemblys.
The rotor ring and stator coil are now sealed inside the hub itself.....this in the hopes the metallic debris issue can be avoided.
For the most part, it is successful but the other things that fail still do.
That being the electromagnet (stator) or the harnesses that relay information.

In general, if the wiring is sound, the hub/bearing assembly requires replacement.

Rob


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## NickD (Dec 10, 2011)

Robby said:


> Each wheel bearing has a speed sensor built into it.
> The sensor is a electromagnet and it is stationary.
> On the hub side of the bearing, there is a ring with, what a novice would call, teeth.....like a gear.
> The two components are the speed sensor.
> ...


Are you saying the reluctors and the Cruze are not shielded? Weird, are shield on any other ABS vehicle I have worked on. Also paranoid with insurance companies, if involved with an accident, even though your car was parked, will claim its your fault because your ABS lamp stays on.

While that Stanford professor says having ABS is 14% safer thus becoming mandatory by congress, read that at the other 86% of the time, they are worthless.

But at least the Cruze has a separate ABS sensor, essentially just a coil of wire wrapped around a permanent bar magnet. Others use a Hall Effect sensor, more expensive, but degrade with temperature.










Some had this sensor integrated with the hub assembly, so have to replace the entire $$$$$ assembly just because of a broken wire inside of that coil.


ABS has two test modes, if the ABS light comes on with the ignition and stays on, it did not pass the static test. ABS master relay, pump relay, pump, and all four sensors are tested for open or shorts. If any fail, that light will stay on. But can come on at about 5-8 mph for the dynamic test, hear that buzz, then tests all the sensors for pulse output, this is where a plugged reluctor can be the culprit.

Since the traction control depends on the same wheel sensors, and if faulty, that lamp should come on as well.

That connector you see on that photo above can also be the culprit, done only for assembly convenience, since these pulses are applied to a very high impedance CMOS transistor, the slightest bit of corrosion can kill the signal. Ran across these as well, just cut them out and solder and water proof them. Its not like I am changing the sensor several time per day and need that connector for convenience. How many times does convenience cause a lot of extra grief? Don't need any more grief.


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## Robby (Mar 1, 2013)

Nick,

Read my post above yours.

Rob


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## NickD (Dec 10, 2011)

Robby said:


> Nick,
> 
> Read my post above yours.
> 
> Rob


Cruze is still using the separate sensor for around 15 bucks, so do not quite get why the hub/bearing assembly has to be replaces, unless that shield is rusted out.

Not really much of a hub/bearing fan, another limited lubricated bearing, doesn't have to be mileage that wears them out, just time, that grease gets rock hard. and even worse when they are made in China.

Not a darn reason in the world the old fashion Made in the USA Timken adjustable bearings can't be use, even in a FWD vehicle. When doing a brake job, can be cleaned, would be out 80 cents for a new seal, and repacked with new fresh grease. Never ever had a bearing failure with these, but they claim people didn't know how to properly adjust them, so now hub bearings!

On some vehicles, 300 bucks each, and if all four fail, 1,200 bucks plus tax, and just for parts. Miserable to replace, because well rusted in. In my experience, another way overpriced throwaway part, even further complicated by integrating the ABS wheel sensor in these things. 

Guess they call this progress, I call it screwing the consumer.


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## Robby (Mar 1, 2013)

The cartridge bearings are the result of two primary things.

Over the years, owners delayed cleaning and repacking the bearings and it was not uncommon to find the spindles ruined from the bearing welding internally and spinning on the spindle shoulders.
That and folks that know how to correctly set a roller bearing have become few and far between.

The other reason is obvious.....the drive axle has to go through the bearing center to power the hub.

Since the non serviceable cartridge has become the norm, you now find them on the non-powered wheels as well and overall the failure rate, as a percentage, has become almost nil.......and, to those that were unaware there are two ball bearings in those hubs as opposed to rollers.

Benifit to that is less rolling resistance, ie, one more method of improving fuel economy.
Overall, there is a cost advantage to the consumer in fuel savings and service expense as long as design life is met.

I understand your resistance to change Nick....I'm old school too and when the cartridge systems were becoming common in the early eighties I looked at the design as a looming disaster myself......it didn't happen.
There were more failures in the early years, but nowhere near what I invisioned.

As pointed out though, electronics.....more and more of it, are the real problem and one that, near as I can see, are just going to become more and more of a obsticle to overcome.

Helps you understand why those of us in the biz have turned prematurely grey......or bald.

Rob


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## NickD (Dec 10, 2011)

I loved the 3-4 transistor HEI distributors and 10SI solid state alternators where we even borrowed NASA thick film technology for superior reliability. And far superior to contact points. Even installed these in my pre-1972 GM vehicles.

But with OBD I and literally hundreds of thousands of transistors to get that same spark, started carrying towing insurance.


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## dealmaker5 (May 7, 2014)

Hello Guys new to the form, but not mechanics. I have a 2013 chevy cruze LS model. That was hit a tad on the left front side. Took out the control arm, rad , condensor , etc. , not a very big deal. All has been replaced , and all the sensors that you are talking about here ( on both front wheels ) were intact but the male plugs on the connectors were either disconnected and the left side one was gone or ripped off the two conductor wire leading to the sensor. So, here is what I did ......the drivers side was Un clipped , found the connector close by and connected it. The passenger side connector was gone ,so I purchased another connector and spliced / waterproofed it on. Now this is a two conductor wire going to the sensor, ( I do not know if they are specific in the way they connect back up , like if it matters if you reverse the conductors, perhaps you can tell me. Anyway with all that connected back up and the hubs blown out with air and the sensors put back in , I still have the lights "on " the dash , abs and stabilitrack. My stabilitrack button on the console will not do anything at this point either. I did purchase (2) new complete sensor harnesses like in the photo above, and about to install them. Not sure if that will fix this issue or not. Will see. My question is if is doesnot do the job , does the ecu have to be reset? Or if not is there anything I can trouble shoot at this point to clear up the lights. Code scan has been run and codes are clear. My assumption is that perhaps a sensor assembly got yanked in the hit causing the integrity of the cable to be stretched, just an assumption , I appreciate any assistance in the matter. Thank u and the car has just 7400 miles on it .


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## Lostiguy (Feb 15, 2014)

Thanks for all the input. Dealamker 5, please keep me posted on how you make out. Drove today and the lights stayed on from start to stop. I have not taken off the wheels to check connectors but that will be my next step. If the wheel bearing goes, does that necessarily mean that the speed sensor is gone too?


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## NickD (Dec 10, 2011)

Typical generic scanners do not show ABS codes, for years, required a GM Tech I or II scanner with an ABS module. Something about liability that doesn't make a bit of sense. In theory at least, ABS is an auxiliary add on system that is not suppose to inhibit normal braking. But anyone can work on their own primary braking system, but not on the ABS.

I said in theory, because if you run across a modulator with a valve stuck closed, that particular wheel will get no braking whatsoever. And if the valve driver transistors are turned on by a 5 volt microcontroller that sees a transient that shorts out the outputs to Vss, all four transistors will be turned on, all four valves will be enegized, no brake fluid passage period, and you will have no brakes at all. Can also be caused by corrupted firmware.

ABS operates by interfering with the flow of brake fluid to each wheel! But it is the law.

Polarity does make a difference, positive spike is greater than the negative one. Shop manuals are written in such a way, where they say, solid state, do not test. Never read anything so idiotic in my life, you need the proper test equipment to check these out, and an ohmmeter is the worst possible tool to do this with. Should show the waveforms.

Can tell you as a long time engineer, designing any component is easy, the real difficult part is how to test it. To make sure its reliable and meets all specifications. Connectors are only used for assembly convenience, been saying this for years, best connector is NO connector. But outruled by production cost. 

Diagnostics are also short of a bad joke, no secondary references, only detects an open or a short, but not if a component is way out of tolerance. Cure for this is to replace with a known good component. But how does one know its a good component if zero specifications are given?

Was talk about hiring hundreds of thousands of skilled electronic technicians when OBD I first came out. Never happened, some guy good at changing mufflers is handling this chore. And you wonder why we have problems.


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## dealmaker5 (May 7, 2014)

So let's say all the sensors have been checked and are brand new and good., should the abs light go out at that point or do you have to have chevy reprogram a module?


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## Jim Frye (Mar 16, 2011)

Did you try pulling the battery cables off for 30 seconds or so to see if that reset things? Oh, yeah, did you reset the stored codes also?


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## dealmaker5 (May 7, 2014)

Ok guys, just got done replacing the new sensor as illustrated in photo above. At the same time I reversed the conductors on the wire coming to the sensor assembly . This cable is polarity sensitive and can be measured with an ohm meter to get your polarity correct. This was my problem. When I replaced the female connector that somehow got torn off in the fender bender , I just connected a new one and did not pay attention to polarity on the 2 conductor wire. As soon as I reversed it and turned the car on the abs light went off and the stabilitrac went off and I got my traction control button on the console working again. My sensors were not dirty at all due to the low mileage on the car. Good luck , hope his helps someone.


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## dealmaker5 (May 7, 2014)

Did not have to remove battery for 30 sec. Nor did I have to remove any codes , the lights just all went off as soon as car was started. And the polarity on cable was reversed for my issue. Good luck


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## NickD (Dec 10, 2011)

We were all darn near 20 years longer the last time we could reset the codes in the vehicles made at that time by disconnecting the negative lead of the battery.

But didn't even need to do that, just needed a paper clip wire to short out a couple of terminals on the diagnostic connector. Could call this the good ole days, today you need a way overpriced scanner to do this. But with most ABS, after the problem is cured, will reset itself.


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## fyrftr422 (Aug 15, 2012)

2012 1.4L Cruze with 253,000 kms. Just had this happen today on the way home from work. Pouring rain and a lot of spray kicked up and about halfway (1.5 hour commute) home both Stabilitrak and ABS lights come on, as well as Service message for both Stabilitrak and Traction Control. Car still ran just fine, pulled into first exit to get gas. Turned car back on, got same messages/lights, but they went out, permanently, before I left the gas station driveway. I was unable to find a techlink bulletin for this, but maybe I just don't know where to look.


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