programming speed sensor after installing 40" tires?

[OrangeCrush]

So here's the deal. When I had the 37's on with 4.56 gears, when I programmed my tuner to reflect that, I would get an abs/brake light on.

The way around that was to program the tuner with 35's and a lesser gear ratio. It worked perfect, my speedometer was on the money and no lights.

Now that I've switched to 40" tires, I keep getting the same light on. I've tried a combination of tire sizes and gear ratios but to no avail... after you've driven for 10 miles, the light comes back on.

I called Diablo and they told me I had to have someone change the values in the ECM for something to do with speed sensor. When I called my GM tech buddy, he wasn't sure what Diablo was specifically asking to be changed.

So, for anyone that installed 40's, how did you get around this?

Thanks,

Mark

[guruerror]

That's weird...I've had 37s and 4.56s for several years with the ECM programmed for such and I've never had the ABS light come on once? Of course...you've got the DMax, so that prolly throws a bit of a curve in there...hmmm.

I know...this comment is no help at all, sorry. I hope you figure this one out.

[OrangeCrush]

Originally Posted by guruerror

That's weird...I've had 37s and 4.56s for several years with the ECM programmed for such and I've never had the ABS light come on once? Of course...you've got the DMax, so that prolly throws a bit of a curve in there...hmmm.

I know...this comment is no help at all, sorry. I hope you figure this one out.

You're right... no help at all.




Seriously though, apparently I'm making the sensors reach their limits and thus turning on this stupid light. Doesn't happen until I'm on the highway, around town, we're cool.

I'm waiting to hear back from a tuning expert.




Mark

[HUMTECH]

I know on some GM's you can go into the ebcm under the special functions menu and set tire size. Not positive if this can be done on an H3 or not

[Yetti]

40" x 3.1415 = 125.66" / 12" = 10.47166 feet in dia.
take the value and divide 5280'/ 10.471 = 504 rotations per mile
the value the ecu needs is the count per mile. so you have to do a little math.

[OrangeCrush]

Originally Posted by Yetti

40" x 3.1415 = 125.66" / 12" = 10.47166 feet in dia.
take the value and divide 5280'/ 10.471 = 504 rotations per mile
the value the ecu needs is the count per mile. so you have to do a little math.

Yup, I understand the problem, I just can?t find someone to reset the parameters in the ECM.

Mark