Bill Dearborn

Did you get somebody to read the codes again after the Service message came back? If not then you don't know which code is driving this message. Depending on what auto parts stores are available in your area some of them have scanners that will read the ABS codes and they will read them for you for free. I know the Advance Auto Parts stores in my area have them while the Auto Zone stores do not.

Inspect the connectors at each end of the harness to make sure they are free from corrosion and that the female pins are actually making contact with the make pins.

Bill

cleanerPA

Yes, i have a code reader that can read abs codes. The same exact code as last time. I cleaned each connector with deoxit when i took them apart.

cleanerPA

It's been a while, but I do have an update.

I think the problem is solved.

I bought the aux wire harness that goes from the body harness to the ABS sensor- Patrick at GM Parts House (colleague of Gene's) told me at Carlisle that it is fairly common that this harness has problems.

Following my local dealer's diagnosis, I installed the aux wire harness today. I cleaned all of the connections with DeOxit, even on the new wire harness. Then I installed it, put everything back together and went for a 15 min. test drive. No codes!

I intentionally launched it hard enough to trigger traction control three times just to make extra sure that nothing untoward was going on- no errors.

I'm very, very happy.

Long story short- if you ever have ABS codes pointing to a wheel sensor, definitely check that wiring harness- it's not that expensive ($26 or so) and it can cause a lot of problems. I can't say that the wheel sensors themselves were bad- the diagnosis was that there was intermittent dropouts in the sensor shown in a snapshot by the Tech 2. Anyway, as a preventative measure, I now have ZR1 hubs- I would have done that upgrade eventually anyway (plan on taking the car to the track).

Thanks to everyone that helped. Bill, you're a fount of knowledge, it is much appreciated.

B y r o n

Glad to hear you finally got it sorted out.

cleanerPA

Okay, it's NOT solved.

I drove the car for over an hour and the same error messages came on again! WTF?

Funny thing is, I shut the car off, turned it back on and then it was fine for another hour without any codes (I was going somewhere so I couldn't just keep on driving).

Same thing happened on the way back- about an hour and it kicked out the same error messages. It happened at the same kind of driving- just cruising along.

Now I'm wondering if there is some sort of computer issue that is causing it to get messed up.

The next thing I want to test is to see if I drive the car with traction control and stability turned off, will it still throw the same codes?

cleanerPA

Another follow up- the car has this same intermittent error- now it is intermittent! WTF?

Drove for 2 hours, no codes. Stopped for lunch, less than two minutes after starting to drive, I get the same error. Shut the car off, restarted, no more error codes for another 1.5 hrs or so.

Then I get the error again on a fairly hard acceleration. What I did notice is that even with traction control off, the car doesn't always apply full power? I wonder if that is torque management interfering. It is definitely triggerable on hard acceleration now.

Now I'm thinking it is not a wheel sensor issue, but rather an EBCM issue- seems to happen pretty easily on hard acceleration.

I also wonder if it is heat-related somehow- it is easier to cause the fault in city driving than highway driving.

Any suggestions? I'm going to have to go in and have another Tech 2 read of the car to see if the codes are the same or different, because all I've gotten is the same C0040 without the additional numbers that tell me exactly what the issue is with the right front wheel sensor.

Chevy Cust Svc

cleanerPA,
I'm going to monitor this thread. Let us know what you end up finding out.

Chevrolet Customer Service,
Justin

taken19

My car started doing this on the track this past weekend. A C5 guy told me it is a common issue in vettes and to check out the EBCM. I will do more research and postif I find anything helpful.

BEZ06

No - it's not a common issue at all in the C6!!!

At least what cleanerPA is experiencing is definitely not common.

What exactly is your car doing???

Are you getting the CEL and codes similar to what cleanerPA is getting?

cleanerPA seems to have one of those very difficult to find electrical gremlins.

You could be getting something that is much more simple, but we need more info to help you out.

Bob

taken19

Bob, thanks for chiming in - I need that!

A little background first... Did the H/C/I swap about 6 months ago and no issues for months (2k miles). About a month ago I started getting the Engine Drag Control Active message once in a while during downshifts. This was after a couple track events so I figured it was because I wore down my front tires faster than the rears. Didn't think much of it...

Last week I got my first Service Charging System message at idle in my driveway. The alternator wire has already been moved away from the plug wire. I do have NGK TR6 plugs, but they have been for 4 months with no issues.

On a road trip to Key West I got the Service AH, TC, and ABS message. I was driving 45 mph, no spirited driving, minor bumps in road, nothing that I think should trigger this. Did not repeat once car shutdown and restarted.

Did a track day at Homestead and started getting TC and AH at high speeds... I think because I was running 275/35 fronts and 305/30 rears on stock rims. Need to swap to 265/35 fronts to fix that. First two sessions went fine, then got the Service AH, TC and ABS on turn 6. Limped in, stopped and restarted car and no issue for remainder of session. Bled brakes between sessions just to make sure. Last session it happened on lap 6. Pulled into put, cycled ignition and the problem repeated in less than a minute. At that point, I called it a day and ended early. Drive home (4 miles) did not recreate problem.

No CEL, and cheap Auto Zone code reader pulled up nothing.

Need any more info? Does all that make sense?

Sean

BEZ06

Hi Sean

Yes, that makes pretty good sense!!

You mentioned a Drag Control message. I'm quite certain that wearing the tires down a little won't cause that. Usually that is only caused by putting larger tires on the rear.

You mention Service AH, TC, and ABS messages. Are you sure one wasn't "Service Tire Monitor"???

The ABS and the tire pressure sensors and TPMS generally don't turn on the CEL or throw codes that you can read with a common scanner.

Have you swapped wheels (do you have track wheels/tires)?

What it sounds to me like is that your tire pressure sensors aren't programmed into your TPMS.

Depending on the model year of the car, the C6 can be a PITA on the track when run without tire pressure sensors, or if they aren't programmed into the TPMS memory correctly (depending on year, some years tolerate running with no sensors better than other years).

Without sensors I can't go into Comp mode, and I've had the AH on my 2006 really jerk the car around when it slams on individual brakes, and it will pull power when trying to accelerate out of a corner until I get it going perfectly straight - it's undriveable and unsafe on the track without sensors.

So....if you aren't getting any codes or a CEL, I'd start off by reprogramming the tire pressure sensors, and if you have track wheels/tires you'll need to program those sensors every time you swap them onto your car.

Good luck, and let us know what you find!!

Bob

taken19

Bob, actually I used one of your old threads to reprogram my track wheels. I have an '05 Z51 model by the way.

The very first time I got the trio was with the stock runflats on a road trip. The problem continued after I swapped to my track wheels. I'm positive it wasn't the Service Tire Monitor message. No other anomalies other than described above. I don't know if the drag control and service charging system warnings are related or not, but I figure it doesn't hurt to post as well.

The track wheels do have TPMS sensors in them and I used the $62 GM tool to reprogram. Worked just like you said.

I'm pretty good in the mechanical world, but grasping for an explanation when it comes to "blue smoke"... If I had to guess, I would say it's either:

- alternator or battery starting to go south
- Wheel sensor is becoming intermittent
- EBCM crapping out on me

I don't feel comfortable running on the track without ABS or AH. I think I could live without TC, but that's a stretch for my experience level.

Other ideas?

taken19

CleanerPA, sorry for hijacking your thread...

Chevy Cust Svc

taken19,
I'd definitely recommend taking it to the dealership. This could be a safety issue. Let us know what you find out.

Chevrolet Customer Service,
Justin

taken19

Justin, please don't take this the wrong way, but I do not trust my local dealer. They only service they are valuable for is their Tech computer. I have found many of their mistakes in the past and do not have a very good working relationship with them.

I trust the opinions and troubleshooting efforts of the forum members Much more than the dealership.

Again, nothing against you or your thoughts.

mikeCsix

I think you may still be looking at an intermitten broken wire or connection someplace. Its too bad you can't manipulate the connections and the wire while the car is standing still to see if it will malfunction and throwing parts at the problem gets expensive pretty fast. I would take it back to the dealer to see if its the same codes as before. I don't know where the sensor plugs in or where the jumper wire connects it back to the harness, but would look really closely at the connections to make sure the pins and sockets all look really good and not bent in any way. The connection to the computer could also have an issue. How feasible is it to replace the harness back to the computer? Is it possible to remove the connection from the computer and use an ohm meter to measure the harness so you can tug and pull to see if you get a break in the connections? Could it be an issue with the computer itself? I know, more questions than answers but intermitten problems are difficult to troubleshoot because it sounds like most of the time it all works great. Just every now and then you get a fault or lost connection that immediately clears up so when you reboot the computer (turn the car off and on) all is well again.

Chevy Cust Svc

taken19,
If you send me an email with your zip code I can try and find a good dealership within 50 miles of you.

Chevrolet Customer Service,
Justin

gsxr_rx-1

I had something similar happening to me. When the the problem happens, get out and check to see if your brake lights are on. It was also an intermittent problem. The EBCM had to be replaced. Since then, works like a charm. No lights on the dash or in the rear.

cleanerPA

I'm going to keep working on it, but I'm in the northeast, so once the weather starts getting really cold, the car is going to get parked.

I need to get a real scanner- right now I just have an Actron which gives me ABS codes, but not enough detail.

GM Power4Life

I don't mean to thread jack. But I am having the exact same problem. C0040 FR wheel speed sensor. Replaced it. Same code comes up. AH/TC/ABS only comes on at 60+mph though. I'm leaning towards the aux harness beig the issue.

I can smoke the tires at launch a cause TC to work, works great. Same with ABS, ad long as I'm below 60mph.
I'm running 255/40/18 front and 295/35/19 rear. I don't believe that's the issue but any guidance would be amazing!!!