Service ABS System, Service Traction Control System
 

I realize that this has been brought up a number of times.
The search also showed that this was usually an electrical malfunction.

My story:
2002 Z06 Stock save 1 c6z06 shifter
Conditions: *Roads wet*, overcast out

Taking a friend for a ride and I entered a slow corner/chicane in first gear and gave it about 50% throttle. The tail hopped and the subject line appeared on the information screen on the dash. I immediately let off and pulled over, restarted, etc. The car still drives and accelerates normally. However, if I cause a condition that would normally initiate the traction control (80% - 100% throttle/1st or 2nd gear), the rear end responds with quite a bit of wheel hop.

I am new to the Corvette community (over from Subaru :) (STI)), and am not yet entirely familiar with the beast. The problem seems mechanical. What happens when this error comes on? Is the traction control malfunctioning or is it in a limp mode (if you will)? Is it possible that the conditions of the road and the wheel hop confused the traction/abs systems and it simply needs to be reset?

Please advise, thanks guys!

search EBCM. :willy:

I hope it is something else!

I had the same message, I would check the ground. It fixed my problem.

Interesting, I am here because a few days ago I was heading to work in my 2002 Z06 with only a shifter mod and I hit a good puddle with the right front tire.

Nothing major, and in fact it is a spot I frequent and hit that puddle a lot. It is one of those that startles you because it makes a lot of noise and pulls the steering wheel just a little.

I noticed the computer dinging at me and ABS was on the DIC.

I figured the ABS had activated as it does in low traction instances like railroad tracks and other similar circumstances.

But it kept dinging and flashing messages.

Turns out it wants me to service the ABS, Active Handling and Traction Control.

It is insistent about this. I hoped it would go away on its own, but it hasn't.

I couldn't care less about TC and AH as I turn them off each time I get in the car, but ABS is important as I don't want to flat spot a set of $1,000 tires.

Plus, I'm sure it decreases the value when you go to sell the car if it is setting off alarms every time you get in or out of the vehicle.

So I'm hoping that with all of them going at once it might be some kind of fuse?

Any thoughts from those who have been here before?

TIA,

Guys .... if you're getting SERVICE ABS/AH/TC messages on the DIC ... then guess what ..... SERVICE IS NEEDED.

Search for posts by trussme or Bill Curlee with the keyword "EBCM" .... there are hundreds of posts on this issue.

Display the DTC codes on your DIC, you can/should search on thoose also. To display the codes, follow these instructions ...

https://www.corvetteforum.com/techti...D=26&TopicID=1


And to the new owner who says he turns off his TC and AH .... you might want to reconsider that for street driving, they are great safety features in a car with high horsepower and the potential for the car to "get away" from you, especially at times such as wet roads, etc. Chevy put them on the car for a reason, sure, if you are on a race track, turning them off may be fine (though that's why there is a COMPETITION MODE - even at the track AH is a cool feature) but for street driving I recommend you leave the systems on. Search and you will find many threads where people say that the systems saved their azz ...

:cheers:

check for a code in the DIC.

I have an issues very similar, finally got a code for the steering wheel position sensor failed.

I'll be tackeling this one as soon as I sort other issues out.

Mine will activate for no reason at all. I just shut it off now.

I will check for the code tomorrow and post it. I didn't think this followed the "100s" of posts on this issue b/c most of the posts described a situation that occurred during normal driving. This occurred during slightly aggressive driving followed by wheel hop.

As to the service light meaning it wants to be "SERVICED", what could be more obvious? Seriously, I know that but I am also not going to take my car to a dealership. I'm the mechanic for my car (unless the problem really gets out of my hands lol) and I'm here searching for answers and advice...

Thanks again guys

The EBCM posts codes when it experiences problems, usually either with its sensors, or internally, or with the BPMV. Your driving style, whether aggressive or normal, had no bearing on the EBCM throwing codes. The wheel hop MIGHT have caused a bad connection to a rear wheel speed sensor to worsen, but a bad pothole probably would have done the same.

The information posted in those 100's of other threads will apply to the DTC codes you find in the EBCM. Driving style is, again, immaterial. There are many many Z06 owners who drive their cars very aggressively at drag strips and road courses and don't get the SERVICE warnings.

:cheers:

What ground?

Ed

Look down.......

or search in the C5 technical area for Electrical issues.

there are I believe 12 or 13 ground locations on our tupperware cars that are layed out nicely from some real genious members.

Check the grounds first before sending your car off to GM Service where they will replace a Control Module but not repair the ground connection which possibly could be causing the problem.

Also, "KNOW" that the battery is fully charged and not partially drained and the battery terminal connections are secure. A weak Battery will cause strange things, maybe not what you are seeing but strange non the less.

Start with easy FREE stuff.

I disagree with your assessment regardless of the 100s or 1000s of posts. (BTW if there are 100s of posts on this shouldn't there be one definitive argument and not 100s? Perhaps a sticky?) The fact is, the EBCM throwing the code directly corresponded to the event on the street. They occurred at the exact same moment and logic would deduce that they are related.

As I stated before, when I pull the codes I will post them

You can disagree with my assessment all you want ... but you might want to "tone down" your attitude .... I have fixed problems like this on my car several times, and I, along with users such as Bill Curlee, trussme, DeeGee, and many others, have spent countless hours helping many other people fix problems with the electronic brake control system.

One of the reasons there is no sticky is often, even with the codes, the source of the problem can be hard to track down. Several years ago, for example, it was recognized that a certain vendor's stainless steel brake lines were causing wheel speed sensor problems .... it took a while to track that one down .... the GM tech line figured it out and users like vetterdstr spread the word. Also the EBCM performs more functions than the User Manual would lead you to understand. Functions such as Dynamic Rear Proportioning and Rear Stability Control are also performed, along with Active Handling, Traction Control, and ABS. For the EBCM to perform all of these functions requires complex interactions between computers such as the PCM and the EBCM, and sensors such as the Steering Wheel Position Sensor, and then the EBCM controls the BPMV using relays to vary hydraulic pressure in the different brake lines ....

There are users on here who have forgotten more than I will ever know about a C5. Evil-Twin is a good example, he's a retired GM engineer who spent years working on the C5, from initial design, through testing of prototype vehicles, to working in the field once production cars were delivered. I would recommend you be cautious in who you challenge on this forum ....

Now let's take your last paragraph in your original post and see if we can answer your questions ....

I am new to the Corvette community (over from Subaru (STI)), and am not yet entirely familiar with the beast. The problem seems mechanical. (Most likely not. The only "mechanical" part of the system is the BPMV, which is the pump that can alter hydraulic pressure in individual brake lines. If the pump has failed, the EBCM will have a DTC set to indicate that.) What happens when this error comes on? Is the traction control malfunctioning or is it in a limp mode (if you will)? (When a SERVICE XXXX message is displayed, that function is disabled until the next ignition cycle. At the initiation of the next ignition cycle the EBCM sets all DTC codes to H status and runs its internal diagnostic test. If the test fails, the SERVICE XXXX message is again displayed and that function is disabled for the rest of that ignition cycle) Is it possible that the conditions of the road and the wheel hop confused the traction/abs systems and it simply needs to be reset? (It resets itself at every START of the engine .... the system only gets "confused" when an internal diagnostic test fails, or it sees either no data from certain sensors, or data that appears to be invalid)

Post the codes and various people on the forum will help you figure out the problem.

:cheers:

Disagreeing with your assessment and showing attitude are not related in any way. Furthermore, what you can deduce through text is very very very limited. Also, please explain to me why I cannot challenge your assessment? I don't know who you are as much as you have no idea who I am. I'm here for answers, not to be impressed by the fact that you have been here since 2000, are a senior member, and apparently have done some reading/turned a wrench on a car. I appreciate the advice but lose the "i'm the expert big brother here."

Awesome response, I appreciate it.
This is exactly what I was looking for:

OK .... :leaving: :leaving: :leaving:

The ground that is connected to the front driver's side frame rail. It is the ground that has an eyelet connector that is attached to a 1" black box connector. Inside the black box can accumulate debris and water which can cause it to corrode. Open up the connector take a wire brush some WD-40 and clean the connectors. Also, check the connection to the frame rail make sure the connector and the frame rail are completely clean. GL

Great info....THANKS! The only time I had the same issue with my Z was after it sat in the rain all night. The next morning a lot of wierd stuff happened but the Z ran great.

ED

Well this morning the DIC showed no indication of the problem existing/persisting. This presents two schools of thought. There is a loose electrical connection and the problem will reoccur. Or...The problem was directly related to the conditions and the wheel hop that occurred simultaneously with the code appearing on the DIC. Time will tell... Nevertheless, I will still be checking the related electrical connections.

Thanks for the responses guys

I think the problem will come and go every 100 engine start up cycles. If the problem comes back check the grounds.

It took several weeks for my car to finally give me a code.

it would hit the active handeling several times a night. Did this for over a month, then it finally went nuts doing it over and over again. I turned it off, then the DIC said active handeling and service vehicle soon over and over again, I had to hit reset for it to go away. then a code was set.

If you got the SERVICE ABS/TC/AH messages, you have HISTORY codes set in the EBCM. In fact the codes are set to H status at the end of each ignition cycle. They will remain in the EBCM for 100 ignition cycles of no re-occurance.

I suspect you either didn't pull codes correctly, as every Corvette has at least a few Uxxxx codes, and you definately have one or more CxxxxH codes if you got the SERVICE messages, or you didn't realize that H codes are left in the computer as a diagnostic aid for intermittent problems.

:cheers:

I haven't pulled the codes at all. I didn't realize they would remain in the EBCM. That's an interesting and quite useful bit of engineering there. I will pull them and post them.

Thanks

So would you like to take back the "I appreciate the advice but lose the "i'm the expert big brother here."" statement ???


The fact is the C5 Corvette is a VERY sophisticated collection of computer hardware/software .... GM has done a HORRIBLE job of marketing how sophisticated the systems are in their cars. Look at the RPO F55 suspension option ... so good that Ferrari has licensed it and uses it in the 599 GTB Fiorano, and Audi has licensed it and uses it for the new R8.

The computers in a C5 manage almost every function in the car ... and if they don't manage it, they monitor it ... and post a Diagnostic Trouble Code (DTC) when they see a problem.

The format of the codes is AxxxxZ where A=the type of code (Powertrain = P, Chassis = C, etc.) followed by 4 digits, and at the end is either a C or H (sometimes both for certain codes) indicating if the problem is Current or History.

These cars are VERY complex .... there are many computers in them, and almost everything that occurs requires interactions between at least two computers .... turn on your A/C and you are "requesting" A/C ... it is ultimately the PCM that decides whether or not it is willing to turn on the A/C compressor, and it is programmed to "throttle up" the engine as the A/C compressor comes on-line so that you don't feel that "hesitation" as the compressor clutch engages.

If you have a "problem" with the car, the best thing to do is to dump the DTC data .... it goes a long way toward helping pinpoint the problem.

:cheers:

:cheers: Yeah, I know. That's why I came here - to see what service is needed so I can do it. Preferably myself. Looking at the other thread on this, I'm going to go through all the grounds with a fine tooth comb this weekend.

As I said, I don't use AH or TC. I find them to be next to useless. But I do like ABS. I don't want to flat spot a set of $1,200 tires in a panic stop.

The search is what brought me to this thread. I discovered some of the others as I continued down my search results. This one was first.

Thanks, saved me looking that up. I haven't checked my codes in ages.

As you can see from my sig, I'm basing my opinions on 8 1/2 years of C5 Corvette ownership, most of them with the Z06. I'm not at all impressed with the AH or TC on these cars. It is blunt and heavy handed in most cases. I'll be impressed when they come up with one that can improve my driving without shutting the car down most of the time. (And they will, they just aren't there yet.)


To each his own.


Again, not in my experience. I'm not impressed with the C5 implementation of AH, or TC. Heck, I think they could improve the ABS but at least it does what it is supposed to do.

I generally save my own. AH and TC are relatively new things. I've been driving for long enough that I learned how to drive without a nannie shutting down the throttle when I choose to put the car into power oversteer and while no one is perfect and I can't claim I've never made a mistake - I haven't wrecked yet. And I find limits from time to time...

Guys.. absfixer.com

150 shipped.

Since neither of these posters has listed his DTC data ..... what makes you think the problem is in the EBCM ?????

If it is a wiring problem to a wheel speed sensor, or the Steering Wheel Position Sensor is failing, then they've just spent money for nothing .... let's do a little diagnosing before jumping to a "fix" ....

:cheers:

Fair enough, just thought I'd throw that idea into the pot. I think the OP should always take the free/easiest fixes first before repairing a part.

For me, I went through 5 different ideas before I fixed it with the absfixer guy. I just scanned the replies and saw no mention of it.

Just Had Same Problem With My Z . It Was The Wheel Postioner Sensor. Which Is Located At The End Of The Steering Column Under The Dash ,driver Side. Part From Gm Cost $20.took Z To Gm For Install 1.5 Hr. Got The Z Back . No More Codes Or Problems. Do A Search In Wheel Postioner Sensor For More Info. Good Luck!!

Since we're all family here and I'm having the same problem, here's my codes, C1214 and C1287. Any suggestions?

i think mine had the c1214 code. had to replace the ebcm. all is well. the part is easy to get to. right on the abs pump. kind of expensive though.

C1214 - The dreaded "BPMV control curcuit" relay .....

C1287 - The SWPS (Steering Wheel Position Sensor) input is invalid

Given that it seems unlikely these would both fail at the same time, here's what I would recommend.

Step 1) Check the EBCM grounds and be certain they are clean. The EBCM is grounded at two points, G103, and G108. The EBCM provides the "ground" for the SWPS ... there is no seperate ground for it.

G108 is located on the right frame rail, next to G104, almost directly below the NEG battery cable.

G103 is located on the left frame rail, just behind G101, and about opposite the BPMV.

Step 2) After cleaning the grounds THOUROUGHLY, and checking the EBCM wiring connectors for corrosion, DELETE the codes from the EBCM using the DIC. Clear ALL codes from the car.

Step 3) Go out for a drive - 15 minutes or so, no need to do anything "aggressive", if the relay that sets C1214 is actually failed, the code will come back within seconds of your engine starting (and your foot is off the brake pedal).

Step 4) Check for codes at the end of the drive. Post here if there are any. If none ... very cool. If the C1214 is back, take a look at either replacing the EBCM with another from GM (which will eventually fail too) or sending in your EBCM to http://www.absfixer.com and getting the problem fixed once and for all.

:cheers:

Sure, I'll rescind my statement. Perhaps first impressions got us off on the wrong foot. Apologies.

I apologize that I haven't posted the DTCs yet. Just hasn't quite made it to the front of the priority queue yet.

-B

two weeks ago I had the dreaded column lock rear it's ugly head. Had to tow the car to the local dealer where they replaced a couple relays and the column lock actuator. I was getting the ABS/AH codes at the same time but they couldn't get them to come back after the column lock issue was repaired. Is this stuff all related by any chance?

I located and cleaned the grounds on the frame at the front of the car by the radiator, are these the ones you are referring to?

Thanks for the assist, Clint

No problem ... sometimes we all have our "bad" days ....

Post the codes when you can and we'll look at them ....

:cheers:

The ones on the front frame, drivers side, is the G103 location (by the radiator). G108 is on the other side (passenger) and further back, almost directly below the battery NEG cable.

The Corvette is different from most cars in that effectively it is a "plastic" body on a metal chassis. The reason this is important is that on your "average" car any electrical component can be grounded directly to the bodywork (metal) it is attached to. On the Corvette the ground has to actually be a wire that leads back to a location on the chassis. If these ground locations become corroded, or a wire comes off, then the component being grounded no longer works correctly, or works intermittently. With all the computers in a modern car, a bad or intermittent ground in a few components can cause all kinds of confusing and seemingly unrelated problems. Keeping the ground points clean on a Corvette helps a lot.

Also, voltage is important. The computers expect to see a consistent voltage level from the sensors and other devices they control. A weak battery can also cause seemingly unrelated and unexplained problems. Always check the NEG and POS battery cables when you are doing an oil change and be sure there are no signs of corrosion starting, or cables coming lose.

It seems unlikely the EBCM and the column lock issues are related, but certainly if you and/or the dealer cleaned ground points to address the column lock, that may have also cleared the EBCM issues. There are only a handful of groundpoints in the car, many are shared by numerous parts of the system.

It sounds like your EBCM is working OK now, DELETE those codes so you have a "clean" record, and keep on :steering:

Have fun out there ....

:cheers:

Problem reared it's ugly head again this mornin...came scrolling across the DIC

**************************************** *********
Current Codes:

Module: 28 TCS Traction Control system ABS
Code: C1214 Sol Valve relay Contact or coil CKT Open

Historical Codes (had an 'H' next to them on the DIC):

Module: 40 BCM Body Control Module
Code: U1160 Loss of Communications with LDCM

Module: A0 LDCM Left Door Control module
Code: B2252 Key Cylinder Switch Fault DCM-LEFT

Module: A0 LDCM Left Door Control module
Code: B2284 Battery #2 Fault DCM-LEFT

Module: AC SCM Seat Control module
Code: U1064 Loss Of Communication with DCM (No SOH Message
Received -RFA

Module: A1 RDCM Right Door Control Module
Code: B2285 Battery #2 Fault DCM-RIGHT

**************************************** *********

I seem to have traction control problems in both my seat and in the rear wheels...

What say you?

Looks like the strikes again...

Where to go from here....

The Door Control and Seat Control Module DTC look like an electrical issue. Possibly at one point in time you had a voltage drop while starting the car (weak battery) and the seat was adjusting itself at the same time. I'd delete them, but watch for a re-occurance. Sometimes these can also be kicked off by the wiring in the "accordion" protection in the door hinge area. Occasionally the wiring inside thee accordion can chafe and short or ground .... if you keep seeing these type of DTC I'd look in the hinge area ....

I'd try cleaning the grounds at G103 and G108, then clearing the code and seeing if it comes back again. If it is intermittent, there is a chance that the grounding is the issue, as usually when the relay fails, it fails for good. Another thing you can try (after clearing the code) is taking the car on a quiet road and "exercising" the BPMV and the relay by making two or three stops that activate the ABS.

If the code won't clear, the best solution, in my opinion, is to ship your EBCM to

http://www.absfixer.com

The site includes instructions on removing the EBCM (the car is driveable with the unit removed) and shipping it.

:cheers:

Thanks for the information. At what level is the AH/TC and ABS functioning now? Not at all? Also, what's the skinny on the functionality of the relay? (or a link will work :) )

With a C1214 set, the EBCM is almost completely non-functional. The EBCM is unable to control the BPMV, which means that all of the EBCM functions that require it to control brake line pressure are disabled. This means you have no ...

ABS - Anti-lock Brake System
TC - Traction Control
AH - Active Handling
DRP - Dynamic Rear Proportioning
RSC - Rear Stability Control (2001 and later)

The EBCM continues to monitor/control your MAGNASTEER system, as it uses a different solenoid to control that system.

Basically you are driving a car from the 1960 era .... you have a brake system that works, but your foot is completely in control. There are no "nanny" aids such as ABS to come to your assistance in an emergency. Another way to look at it .... when/if you remove the EBCM and send it to absfixer ..... the car will drive the same (almost - steering effort may feel different) with the EBCM removed as it does today with a "disabled" EBCM. ALL of the above functions are COMPLETELY disabled.

The EBCM is basically a computer, it has no "mechanical" capabilities. The BPMV is a mechanical device that is able to either increase pressure in a brake line, or decrease pressure in a brake line, but it has no "brain" within itself that decides when to change the pressure in a brake line. The EBCM is the "brain" that controls the "dumb" BPMV. The C1214 simply indicates that the EBCM no longer has the ability to control the BPMV. Once the EBCM realizes it cannot control the BPMV, it sets the C1214 and "disables" (shuts off) all of the functions it controls through the BPMV.

:cheers:

Great information. I started reading up on the abs system on absfixer.com. Parts breaking always yields an upside and downside; at least to me. The downside is obvious and the upside is getting to learn something that I would not have otherwise learned.

Anyhow, I'm going to check the grounds this weekend. It is currently nasty, rainy, wet, icy, etc here in lovely DC..

Great post. I will confirm that the steering will feel different with it removed. I drove about two weeks with it off and just put the fixed unit on from ABS FIXER and immediately noticed that I had full power steering back.

It is quite driveable with the EBCM off, and you really only notice the power steering difference in parking lots.

I'm reading through this thread due to getting the service ABS/TC message with code for RR speed sensor (coincidentally I just let the dealership fix that problem and it was fine for about 3 weeks). Anyway, I came across this point about the fact the PCM controls whether or not to turn on the A/C and wanted to point out that my 1989 Ford Probe did the exact same thing. The electronic A/C control sent request to the PCM via a ground and the PCM provided the ground to the A/C clutch relay while idling up the engine. Irrelevant to this post, I know but I couldn't help pointing this out.

Thanks for all the great info guys. I'm going to finish reading post and will take a look at the connector on the RR wheel speed sensor as soon as I have time. Sounds like checking/cleaning grounds could be a good thing as well.

Same message. Dealer replaced a sensor in the steering column. Cost almost $500...... Ouch...!

OK, so here I am at 11:15 at night and just got my 09 delivered a few hours ago. Drove it ONE MILE and the T/C and ABS lights come on and say they need service. The car has 8 miles on it.
Nice start GM.............Anyone have any ideas???

I won't even pretend to be smart compared to many on this forum, but it seems to me that there's only one obvious answer here...... take it back to wherever you bought it and tell them to fix it.