Y2Kvert4me

I beg to differ.

My car has a bad steering wheel position sensor.
MOST of the time, it just trips the C1287/C1288 faults, which shuts the AH system off.

On a handful of occasions, the sensor apparently didn't error quite enough to trip the codes, but err'd enough to engage active handling on the freeway. Never a violent brake application, but enough to be noticible.
After the first few times it did that, I was wise enough to realize the above situation (violent brake application) is certainly possible, and I've gotten into the habit of just killing AH at startup to make sure that doesn't happen. I usually still get the codes, but that's nothing compared to an unexpected intrusion of the braking system.

gpracer1

Dude, fix the sensor. It cant cost more than your life!!

themonk

He's in Canada, I don't think that NHTSA has any jurisdiction up here. I believe that he would have to contact Transport Canada.

The Monk!

Y2Kvert4me

I'm lazy. Pushing the button on the console to shut it off is easier.

CHASLS2

OUCH! What a read.

gpracer1

Pics?

RichieRichZ06

I am sorry. I did miss read the original post and was under the ***umption that it was caused by the ABS, not the TC/AH. In this line of work, I have seen and heard it all and normally the fault is on the human behind the wheel, not the computer in the car. Like I said, I do appologize for jumping to conclusions. The engineer threw out the document ID and I just took it and ran with it. I am in this business to help others, especially the Corvette owners that are like myself. I am about to do some digging and I will try to help you build your case under the TC/AH argument.

The EDR can only be requested by a governing agency like the courts or NHTSA. The insurance company could open a case and request the info be pulled. When I called the engineer back, he said the info should be in there. It is not only for airbag related accidents, but any time that the vehicle senses it is about to crash it will record for a few seconds.

I just dug up this on the GM Service Information.... Does it help, as this is a document directly from GM???

Once again, I am here for the Corvette owner who is truthfull, upfront, and needs help, so if there is anything that I can do on the GM end please let me know.

Document ID# 1750541
2001 Chevrolet Corvette


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Subject: Unwanted Active Handling Activation DTC C1282 - keywords ABS active brake EBTCM Stabilitrak #PIC3844 - (01/12/2006)



Models: 1998-2004 Chevrolet Corvette




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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Some vehicles may have a concern with intermittent unwanted activation of the Active Handling System. The Yaw Rate sensor signal can usually be verified to be changing at the time this occurs. DTC C1282 will likely be present in the ABS module.

Recommendation/Instructions:
Check the Yaw Rate Sensor for a missing or loose "Pencil type" bracket. This bracket is supplemental to the main bracket of the Instrument Panel Carrier and is intended to provide extra support. Without this bracket, the sensor will "bounce" under certain road conditions causing the concern. If the bracket is missing part number 10409133 will need to be ordered and installed to correct the concern.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.



GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION


© Copyright General Motors Corporation. All Rights Reserved.


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Document ID# 1750541
2001 Chevrolet Corvette

qwkz06

I apologize if my initial post was too sceptical or brash. I really do feel bad for your friend. He is not the first to get bitten by a new (to that person) Z06. Tire condition and road condition can play a big role in a loss of control situation. I can however tell you that my Z06 has spun the wheels in 3rd gear at the track. Of course I was hitting it hard.

One of the things about vettes that is different from most other cars (especially old muscle cars) is that they corner and handle so well close to the limit it is easy to think that the car is planted while accelerating at fairly high speed in even a little corner then have the car get loose. I don't know what the weather was like or what his tires were like but cold weather on worn Supercars can be exciting to say the least.

I won't comment further on your friends "electronic nanny" comment except to say I also run in Competition mode most of the time to avoid surprises. That being said I have run the car with AH/TC off and she will get very sideways if you don't watch out and like I said earlier, in a vette you can push the envelope in even a little corner so when she goes it is catastrophic.

By the way, the SDM does record near deployment event information so a download of it could be helpful. There are plenty of independent engineers and accident reconstructionist that have the Vetronix equipment to do the download but If your friend is serious about claiming the car caused the wreck he better be careful about potentially altering the evidence.

Good luck in your quest for information. While I remain extremely sceptical I look forward to a documented conclusion.

Blue Angel

No problem.

In fact, your bulletin is EXACTLY the type of information we're looking for! This bulletin jives exactly with the story of a friend who talked with a GM tech guy... the vibrating yaw sensor causing havoc with the AH system... curious that the road he was on is very smooth, but who knows.

Thanks again, and keep the bulletins coming!

Fair enough.

How come you can't get your car to spin going into 4th? Maybe I need to give you some shiftinging lessons...



ALRIGHTY THEN!

Some GREAT information is coming out here, please keep it coming!

vetteman9368

i need to do the same thing on that braket. where is that sensor located at?

I have triggered the AH on a WOT 3/4 shift in a straight line. its freaky to say the least

Blue Angel

As far as I know, the yaw sensor is behind the radio or climate control in the dash, apparently not hard to get to. I haven't ever gone in there on my car, so I'm not 100% sure. Once we go into my buddie's car I'll let everyone know.

gpracer1

According to the service manual its to the left of the ash tray under the climate control.

FiberglassFan

Subscribing to this thread....

Here is an example of why I am SO GLAD my 98 does not have the A-H option. I would NEVER have it.

1998 GTR

I know there's insistment that he was just "cruising" at 70mph and the CAR just went crazy. But for my money a car doing 70mph on a dry road does NOT carry enough kenetic enrergy to first of all "skid across three lanes" (which will scrub a VERY significant amount of speed in itself) AND then "flip and tumble for over 200 feet" AND take out "150 feet of fence and guardrail" AND throw parts ACROSS a major highway to a frontage road!

That sounds a little more like someone not real familiar with a new car, having a little fun at the mid to top end of 4th gear (nothing crazy, but maybe closer to 90-100+mph) and then going for 5th gear, but hitting 3rd gear instead - Yep, all hell would break loose! And from an onlookers viewpoint, for "no reason at all". It would APPEAR than he was just going in a straight line and then the car suddenly swapped ends.

AND all of this just happened to occur within the first few miles of him driving a newly-acquired high-power sports car??? I'm sorry, but despite the verbal claims of the driver (about his speed, style of driving at the time of the accident, and claims of what other people said), if you look at it from an unattached point of view, it seems all the evidence and circumstances point to the syndrome of "crash it within the 1st 100 miles" typical of an over-confident buyer of a performance sports car or motorcycle.

I've gone sideways (past 90 degrees - UNRECOVERABLE) at 100mph (on a race track). And if you do it correctly (as you say his experience would infer) and go "both feet in", you come to a very controlled stop in a fairly short distance, and with no more than 180 degree rotation. And that's at 100mph! Skidding across three lanes, hitting a ditch and then a fence and then a guardrail and then rolling SEVERAL times is just NOT consistant with ANYTHING happening at 70mph! Even a faulty Active Handling System CANNOT break the laws of physics.

Just an objective viewpoint . . .

Glad he walked away!

1998 GTR

A WOT 3-4 shift can very easily break traction (as the thread's author points out). In such a case, if there's ANY sideways movement (that the driver may not even feel), the AH should be activated! Nothing there needing repair! The system is working as designed.

AH simply is NOT a "get out of jail free" card for inexperienced driving! Anyone who has not pushed their car PAST it's limits (in a safe environment) simply does not know where the "EDGE" is, and will invariably be surprised when they hit that edge unintentionally. In fact, if a driver has never driven their car PAST control, they will feel like the CAR went "freaky" because they don't know what it feels like to have pushed past the car's limits.

For the money you might spend on chasing AH issues, try spending that (or less maybe) on a few HPDE's. THEN see if it feels like the car is going crazy, or if it just feels like, "Oops, there's the edge!"

Plus it's a whole lot more fun than chasing non-existant electrical/computer glitches!

Dave

7898VETTMAN

I'm With Fiberglass Fan.i Will Stick With My 98 No A/h

vetteman9368

been there done that, won lots or races (drag, oval, and a few roadraces) back in the day. the car was going straight, shifted 3/4 car pulled to the right breifely as the AH came on. Then the service AH light came on and the code was for the yaw sensor. btw its not fun having the car try to change lanes on you at 100mph. If I was a newb driver i very well might have ended up like the original poster's friend

Blue Angel

I appreciate everyone's skepticism... as I stated earlier I was very skeptical myself until the facts started coming in.

Two other drivers put him at roughly the same speed he reported to the Police, and that is documented right in the Police report. Skeptical or not, that holds water with me and it will hold water in court, it therefore should hold water with everyone here.

Yes, the car lost speed before hitting the ditch. The hwy. is three lanes wide there, plus the shoulder. He was already in the left lane, so he crossed two lanes and the shoulder, probably 40 feet of asphalt. Since he wasn't going directly sideways, more like a 50 degree angle, he probably slid over 70-90 feet of asphalt.

A healthy, stock Z, braking under optimal conditions (good pavement with warm temperatures) will stop from 60 MPH in roughly 110 feet. Since the car is capable of decelerating at a much higher g-load in a straight line under braking than it can maintain in a cornering situation, you could say that if the car was sliding sideways it would take much longer than 110 feet to stop from 60 MPH. Throw in the cold pavement that night and it would take even longer to stop, especially when you consider that the asphalt on the 401 is anything but grippy.

Since doubling your speed quadruples your stopping distance, let's try something... lets assume that under the cold conditions the car would take 140 feet to stop from 60 MPH if it was sliding sideways (knowing that under braking it can do the same in 110 feet in good conditions). If the car slid half that distance (70 ft) on asphalt before going into the ditch, it wouldn't have lost any more than about 25-30% of its speed before it hit (I don't have the formulas handy to figure this out properly, but since the relationship between speed and distance travelled under braking is far from a linear one, this can't be too far off. If anyone can chime in with a formula to figure this out, please do!).

If the car lost 30% of it's original 70 MPH velocity, it still would have hit the ditch at about 49 MPH. The car was cartwheeling and bouncing through the ditch and fence, actually landing on top of the fence at one point, before coming to a rest on its roof approximately 200 feet from where it originally left the asphalt. Since the car wasn't slowing down very fast once it hit the ditch (well, compared to braking on asphalt anyway), this sounds pretty beleiveable, especially since he was travelling 70 MPH, not 60.

True, this is just a hack approximation, but it shows that it's possible. Please, if anyone can figure this out with a formula of some sort, please chime in.

I appreciate that this is a public forum and everyone will have their opinions. Unfortunately, I'm not speculating as to what the driver was doing with the car that night, I'm trying to figure out if the car applying one or more brakes randomly could have been the cause of the initial loss of control.

I'm trying to keep this from becoming a "What do you think happened?" thread, from a "Could the EBCM/AH have played a part in this crash?" thread.

I appreciate everyone's involvement, but I'd like to keep this on track (no pun intended).

Blue Angel

More and more GREAT info is coming out. Thanks!

Let's keep these experiences rolling in!

RichieRichZ06

Now that all of our curiosity and interests are peaked, can you please post all the relevant GREAT info that you are finding in other areas? I'm sure that everybody wants to know what else is turning up. I do in fact have a call into our field rep to see if he has heard of any accidents caused by the EBCM, but have not gotten a call back yet. If he has any info, I will do the same and post it here.