ABS tire size Fix?

[Mike637]

i have a 2002 chevy silverado 2500hd, 6.0L, 4L80E trans., 4.56 gears, 37" tires.
Does anyone know how to figure the numbers manualy in the speedo section so i might be able to stop the abs lights from coming on?

[camaro1]

you need to get the correct numbers in the pcm

then you will need a gm tech 2 and go into the abs module and choose the largest tire size listed and re-calibrate the abs module, i have done this several times and it worked fine

[jimmyblue]

It's peculiar that any straight tire size change would
bother ABS, it's supposed to be looking for wheel
speed -difference-. If the tires are identical and
the system is 4-channel then it should not care.

Might be something like a wheel reluctor out of
position, messed up during wheel swap or gear
changes? When did the problem first show up,
after what?

[jackedupcanyon]

Did you take the stock tune/speedometer settings, input your new tire + gear size and use the auto scale transmission tables?

[EC_Tune]

Jimmy,
In the trucks, the ABS speed pickup point is the tailshaft (Speedo) output. So if you go and change things there will be a descrepency between the front (unchanged) and rear (changed). The ABS system will "allow" a 10% deviation before it declares "foul".