Traction Control, A Dad's Delema

My daughter has a 2004 Impala, with 120,000 miles on it. It has done pretty well, except for intake gaskets, etc. The latest problem is with the traction control. It started with the light coming on. She took the car to Midas in Austin, Texas, who told her it needed both front wheel bearings. I almost vapor locked when I heard the price, but did it anyway:crying: .
When the car came back, it did not behave well. She took it back, they screwed with it some more. It still did not work. She took it back, They responded by firing all of the people who work there, and all the rest of them acted dumb.
This went on for several months with her complaining about the car. Finally sent her to a very reputable shop in Austin, who replaced one defective hub, and the back brakes which had been pulsing, and had worn out. Now the car tries to engage traction control only in a parking lot when you crank the wheel, and try to accelerate. The light also comes on. Took the car back and they hooked the scanner to the car and have driven it for two days. They finally got it to mess up, but even though the light came on, and the traction control tried to engage(again only in a parking lot when trying to back out of a parking space), it registered nothing on the scanner, and stored nothing in the computer. Everyone is baffled. Any ideas?

Is the ABS actually engaging or just the light on the dash coming on ? Check the ABS connections at each wheel .If a connection is loose , sometimes the ABS light will come on . Often when this happens , the " trac off " light will also come on . I'm not sure if this is the same as your situation but it's worth checking . Let us know what you find out ! Good Luck !

Did you have an abs capable scanner on the car and look at comparative wheel speed inputs?

Yes, the traction control is trying to engage. Yet, only in the situation described. I have checked with the mechanics, and it is a traction control capable scanner.

Our 2002 Impala LS had the Traction Control light as well as the ABS Light and you could hear the ABS brakes working! To add fun to everything, the Service Traction Control light started coming on as well and the Traction would turn off.

I checked both front hubs and they seemed tight and secure with no play and free turning. This car had done this for awhile so I changed both front hubs myself (I figured if one was going bad the other probably would soon as well) and it fixed the problem. Both hubs seemed ok but under a load, who knows. Could have been a sensor in one of them.

No telling what GM or a mech. would charge to do this as it takes awhile to do and it and makes it alot easier to have someone turn the wheel for you while removing bolts. Auto Zone wanted $129.09 for the best brand each while O'Reilly wanted $123.99 so I went with that. Get the best brand out there! This isn't something you want to do again anytime soon. The unit comes complete. You can't separate the sensor from the bearing or the bearing from the hub as it's a sealed unit. I wish it would have been as it would have been cheaper but it's not.

Like mentioned before, check the wires at the sensor. I would think the mech. would have done this but who knows. Also you might check the plug next to the master cylinder (big plug) and make sure it's plugged in good. You will see alot of brake lines coming off this. It's a controller.so....

Good Luck!

A question... If you hit the "Trac Off" button to turn off the traction control does that also disable the ABS???

A question... If you hit the "Trac Off" button to turn off the traction control does that also disable the ABS???

Yes. Both ABS & Trac Control gets its data from the speed sensors in the hub bearings.

I am planning to replace my bearings due to a GM tech that "indexed" the bearing wrong and put the wire out at the top of the housing instead of the lower-rear area. This caused the tech to pull the wiring up and strain it to fit the connector and make a short, over time, and now causes problems.

Yes. Both ABS & Trac Control gets its data from the speed sensors in the hub bearings.

The Trac Off button does not disable the ABS. It only turns off the traction control. ABS will still work.
You are correct that both ABS and Traction control get their info from the wheel speed sensors, however.

The Trac Off button does not disable the ABS. It only turns off the traction control. ABS will still work.
You are correct that both ABS and Traction control get their info from the wheel speed sensors, however.

I guess I should have expounded a little there. IF you are having issues with the TRAC sensors, then you cannot just disable the TRAC control as ABS will still have issues as well. You are right that disabling TRAC does not affect ABS. I meant to say that disabling TRAC will not make the problem go away if he is having sensor issues and that will affect ABS as both get disabled when there is a sensor issue.

Yep. If all four sensors are not reporting similar speeds, no more TCS or ABS.

I just want to make sure that the OP was saying that the Traction control light is coming on, NOT the ABS light - I mean that is what he was saying? I don't see him saying anything about ABS coming on.

Just FYI: I had the SAME THING happen to me - my trac. control light would randomly go off. I also had other problems with the vehicle. (random lights flickering, security light coming on, etc...) Sounds like this is a possible issue with your BCM. Which if it is, its honestly not as bad as people think. You could buy one for $80, and get it programmed for like $50...

Not saying out couldn't be sensors or anything, but just trying to say that this has happened to me on my Impala as well - but still could have nothing to do with your problems...

I pretty sure the TRAC/ABS EBCM (Electronic Brake Control Module) don't interface with the BCM at all, just the PCM.