2008 Silverado has 35s and 4.11s. Got the truck tuned. The speedo is on But the abs light will come on. I hooked up the tech 2 and the Tailshaft is reading the correct speed as the gps and speedo but the front wheel speed sensors for the abs are off 5-10 mph depending on speed. Is there anyway to correct that?

 

measure the actual height of the tire. Typically if they say 35 on the side they are actually a 34. The abs usually doesn't trigger if you keep the actual tire and programming on the ecm tcm side to 34.5. Otherwise your going to need to flash the abs module

 

Thanks for the info. How do you flash the abs?

 

You used to be able with a tech 2 but I was told recently that you couldn't anymore but I do not know that for 100%.

 

It believe it was under the EBCM. You enter the tire Size and rating. You can do something similar under the brake's around the automated bleed procedure.

You can not change the gear ratio configuration, that has to be done with tuning software.

 

I've found it is what the stock tire size is determines how large you can change it to. I have better luck changing the revs per mile field. The very first one in the list with HPT. I've found that the max difference I can enter without setting the lights is about -39 rpm. Then I manually scale the shift and lock up tables with the manual scale tool. One thing I haven't tried is putting in a higher gear ratio to make up for the tire size difference and see if I can get the speedo correct that way without setting the lights. And I always heard if you want to edit the EBCM it has to be a tire size that was offered an an optional tire size for that vehicle. I don't think you can just put in any size tire but I'm not sure on that.

 

GM has various sizes listed. Even some in the 33 and 35 range depending on the year of the truck.

 

Thanks for the info guys. I have a tech 2. I have changed the tire size in a gmt800 but I can't find that option for the gmt900 trucks. My software is up to 2013. I think they removed it for those newer trucks.

 

I believe you have to go into the drives side door module on the GMT900's I know thats were the TPMS settings are.

It's there some where, but they hid it...

 

If you find it post it up, I couldnt find it.