I was hoping to get some info here on the Tech site after posting this at the General...

I was driving this morning on the highway, going straight on an on-ramp and all of a sudden got "Traction Control Active" message and the power was shutting off. It did it twice this morning, but on the way home tonight everything was as normal.

I pulled the codes and the only thing I think might be related was C1255H. The only thing I have been able to find is that it might happen if the diameter is not 1/2" or 1" different on the rear and front tires/wheels.

I have a '98 with 245/40/18 on front and 275/30/19 rear. I also had little bit of low tire pressure on left rear.

Could the tire sizes I have affect like this? Or would it maybe be something else? I bought the wheels and tires about 6-7 months ago, and I am wondering how could it just now affect the traction control...

I need your guys help! I am not looking forward to driving to work every morning on the side of the highway idling. Or spending a fortune trying to figure out what is wrong..!!

Thanks in advance,

Suvi

 

Hello--the diameter of your fronts are ( 245-40-18 ) 25.72"
the diameter of your rears are (275-30-19 ) 25.50"
The rears need to be a LARGER diameter than the fronts --as close to 1/2" as possible--Yours are opposite--
Yes this will not only give the traction control system mis-information BUT can cause the ABS braking system to not work properly as well --especially on a panic stop situation--
Like you said-- probably you had some low cold tire pressures in the back so it was really way off and threw a warning code--

Also--did you re-program the new tire sizes into your computer ?--Needs to be done--If not your speedo is off--your shift points are off-Lock up converter is off--computer is picking the wrong timing #'s because the cruise load and speed is wrong--goes on and on----
I would deff. correct it somehow--smaller fronts or larger rears

 

If your tire size is incorrect, the EBCM (Electronic Brake Control Module) will make "bad" decisions. The EBCM expects to see your front wheels turning FASTER than your rear wheels. It uses the "wheel speed sensor's" at each wheel to determine what is happening. When it sees rear wheel speed exceeding the front wheel speed by a preprogrammed amount, the EBCM assumes the rear tires have lost traction and the EBCM commands the PCM to reduce engine torque. If the EBCM continues to see rear wheel speed faster than the front wheels, it will even generate brake pressure to the rear wheels to try and get all of your wheels spinning at the "correct" speed.

Programming the PCM for the correct tire size will solve some issues (speedo correction, shift points, etc), but the EBCM is ignorant of tire size and will still intervene at times that may not be appropriate.

You should look into tires that are closer to what the car left the factory with .... the rear tires should have a larger diameter than the front tires.

If you can't do this, understand that the EBCM may intervene at times you don't expect it too .... it is just doing what it is programmed to do .... monitoring wheel speeds and intervening when they no longer fit within programmed parameters.