Traction control going off erroneously

Yes you need to check the line of sight for each of your hub sensors and see if any trash has gotten in there with the backing plate or whatever got rusted up and slapped around that could have damaged the tone ring on that wheel You need to have a look at that anything obstructing the tone ring from the sensor is a no-no can cause just the kind of problems I think you're having mismatch tires will do the same thing I imagine if you got two different brands of tires in the same size they could be off enough to make this problem rear it's ugly head if you're not careful.

 

First thing I would do is watch live data (graphs would help) on the 4 wheel speed sensors to see if you can tell which one is causing the issue. I use Car Scanner by Stanislav Svistunov on my iPhone and a cheap $12 OBD2 bluetooth dongle, but there are other options.

 

In Techstream, or a comparably-complete scan tool, pull up the "ABS History" display. This will show the most recent four times ABS or VSC got triggered, with the speeds of all four wheels, steering angle, yaw, and lateral and longitudinal g forces at the time of triggering.

To you, there is no reason for VSC to engage, but it clearly is seeing a reason. The history display should suggest what its reason was, and then if you see that one of those inputs didn't match reality, you know that's what needs to be fixed.

 

Well that will do it the two mismatched tires definitely will make the skid control act funny I've done this on my car several times by mistake change the tire back to the correct size so they all match and this problem is gone I did it on another car just to see and absolutely the same thing skid control keeps activating won't let me get up to speed blah blah blah terrible change the tire make sure they're all the same and this problem is gone and the car goes 80 miles an hour so unless there are problems with the speed sensor or one of the sensors at the wheels which you should get a code for your tire size if you is definitely more than likely causing the intermittent skid control

 

If that's what's doing it, you oughtta be able to see it in the activation history.

 

It's funny you wouldn't notice this the minute you changed is wrong size tires into play. That's what happened to me Just one tire a 195 versus a 185 all the other numbers being the same Bam VSC and track light coming on and off slow in the car down soon as it went off the jack stands change the tire never saw that light again till I hit a rain puddle

 

The steering column has both a torque sensor and an angle sensor.

The torque sensor is used by the power steering assist, but not by the stability control.

The angle sensor is used by the stability control (and parking guidance if you have it), but not by the power steering assist.

 

And you're still doing all this with mismatched tires on the car Am I correct and believing that? Until you change that and all four tires match you will have similar problems not saying that something else can't be causing this but why are you beating this to death without getting the four tires to match they don't have to be a match set or anything like that You don't have to go to the tire store today but it would be nice if they were all 185 65 15s or all four of the same numbers whatever that might be in your world then let me know or us know if the problem still persists. But watching all the freeze frame data right now I don't think is really going to help you other than watching the freeze frame data to for whatever reason.

 

It's not that any particular reading from the yaw sensor by itself would indicate a skid. Any time you normally turn a corner, there is a corresponding rate of yaw and lateral g force, and they should be what is expected for the speed of the car and the steering angle, and the difference in wheel speeds between the inner (shorter path) and outer (longer path) wheels should also correspond. When all of those readings make sense together, the stability control is happy.

The VSC will be triggered if you have a yaw rate less than the speed and steering angle should produce (a plowing skid), or greater than what the speed and steering angle should produce (a spinning skid). Or if the wheel speed differences are not what they should be for the curvature being followed.

So the "ABS History" display, which will show you the snapshots of all of those values from the most recent four times the system decided to trigger, offers an easier way of figuring out what caused the triggering, compared to simply trying to watch those values in real time.

 

Have you tried the Freeze Frame option (looks like a 3.5 floppy disc in the main menu)? I've never had the opportunity to try it, but have always been curious if it'd work for something like this.

 

We had anti-slip triggering like crazy, after a "professional" brake bleed (previous vehicle) left on rear corner's brakes completely inoperative.