Tire size reprogramming?

[tunerlover3]

So my ABS light has been on since a day after I put my GXP rims on.

 

Im pretty sure its the rims but I havent actually scanned it yet.

 

Is there a way to reprogram the abs system for bigger tires? Or is that just for the newer gm vehicles?

 

I have a GM tech 2 at school.

[White93z34]

it is something else, so long as all the wheels/tires are the same size.

 

hook it up to the tech2 that should tell you what is wrong.

[tunerlover3]

They are not the same.

 

I went from 225 65 16 to 255 45 18 in the front and 225 50 18 in the rear.

 

Ill have to hook it up anyway though.

[RobertISaar]

hmm...

 

255/45-18 is 27.04" diameter

225/50-18 is 26.86" diameter

 

only a 5 revolution per mile difference....

[carkhz316]

Tech 2 won't fix anything for you buddy (jK). I've been down that road before and we had all the cat's meow for scan tools at the tech I graduated from. More than likely: you have a bad wheel speed sensor (or did this just happen since replacing the wheels?) Otherwise, I was rolling on the 17's that are currently on my '92, on the 98 for awhile when I first got them, and it never threw a code or light, and my speedo was off by like 5mph at highway speeds. In your case it might be because of the two different wheel sizes, or just the drastic change in overall wheel size comparing to vehicle speed.

[Galaxie500XL]

If you've still got the original wheels and tires, put them back on the car, then drive around.

 

Cheap, no special tools needed, and you'll get an answer very quickly.

 

If the ABS light stays on with the original tires/wheels, look at the wheel sensors.

 

I doubt it is possible to program the ABS computer to ignore the speed difference; even if you could, doing so would make the ABS system less effective, as it would be less sensitive to speed differences between the front and rear, making lockup more likely.

 

If this resolves the ABS light issue due to the different diameter tires front to rear, you have 3 choices,

 

Keep the original wheels and tires on the car

 

Ignore the light

 

Put the same tire size on both ends of the car.

 

I'd pick #3, if it were mine.

 

 

 

 

 

[Regal_GS_1989]

The ABS system shouldn't be THAT touchy, that it requires all wheels to spin at exactly the same speed. If it were, you would be triggering the ABS at almost every stop. Also, The front wheels should be allowed to spin faster than the rears without knocking out the ABS system, other wise, it would get knocked out any time you spin your tires.

 

Personally, I would start by scanning it to see what is up. If it is a sensor reading 0, check all the wiring. It is possible that one of them got damaged in lifting the car to change the wheels.

[Imp558]

Mine is pretty sensitive, my light comes on any time I get a little wheel hop. It wouldn't surprise me if the ABS control module is pissed about the different tire sizes. The Tech II shouldn't be able to help with a custom program either. You should do the old rim/tire combo for a few blocks and I bet that makes it go away. If that's the case there may be a geek way of fooling it by using 1:1 matching transformers and stealing 2 signals from 1 sensor on each side.

[RobertISaar]

Mine is pretty sensitive, my light comes on any time I get a little wheel hop. It wouldn't surprise me if the ABS control module is pissed about the different tire sizes. The Tech II shouldn't be able to help with a custom program either. You should do the old rim/tire combo for a few blocks and I bet that makes it go away. If that's the case there may be a geek way of fooling it by using 1:1 matching transformers and stealing 2 signals from 1 sensor on each side.

 

the problem with that is the EBCM won't know if the rear wheels(if the front sensors are read) are starting to lock up....

[Imp558]

Mine is pretty sensitive, my light comes on any time I get a little wheel hop. It wouldn't surprise me if the ABS control module is pissed about the different tire sizes. The Tech II shouldn't be able to help with a custom program either. You should do the old rim/tire combo for a few blocks and I bet that makes it go away. If that's the case there may be a geek way of fooling it by using 1:1 matching transformers and stealing 2 signals from 1 sensor on each side.

 

the problem with that is the EBCM won't know if the rear wheels(if the front sensors are read) are starting to lock up....

 

Yeah, it's an ugly fix but it would eliminate the ABS light and should leave the ABS functional at least somewhat. I suppose another approach could be to use 2 of Dakota Digital's VSS scalers to correct 2 wheels. That's like $100 though, the 1:1 transformers are cheap. I wonder if the ABS is even able to work at all now.

[RobertISaar]

if you want to go really cheap, just go with a plain DRAC.