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ABS light. comming on.

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Berto

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Discussion starter · #1 ·
Hey I'm a new comer here! I recently bought a 03 Mach1 2 weeks ago. Great car very quick!

The only issue im having with it is the ABS light keeps coming on at highway speeds. Then as soon as I shut the car off it goes away until I get on the highway again. I used my scan to see what is going on and it says its code C1222. Now that is Wheel speed mismatch... Using the scan tool I can see that the two front wheel are showing the same speed but the rear ones report that im going slower? The difference is between 3-5 miles.

The car has some power adders. Is it possible that its has different gears? Or how can i fix this? Any input would be great thanks

-Berto-
 
#2 ·
Factory wheel/tire size?

If it does have gears and they are causing it for whatever reason. Usually the only thing gears will effect is the actual speedo and odo readings then youll need to look into getting a tuner.
 
#4 · (Edited)
Just from a quick look i think that *should* be your problem right there. Especially with your fronts 3-5mph faster than the rears.

17 in the front 18 in the rear with same aspect ratio. Front outer diameter is an inch smaller than the rear meaning the fronts will rotate faster than the rears.

Get a tuner, find the rev/mile spec for your rear tires, then set the rev/mile to needed with the tuner.
 
Discussion starter · #5 ·
Ok so its not a huge issue. I was thinking of getting different tires for the rear. Some that are not so tall. My fenders are eating up the side wall of the tires. And it don't help that the car is lowed a little.
 
#6 · (Edited)
Ok so its not a huge issue.

Its throwing off the speedometer and odometer as well. New tires also wont do you much good. I dont see how you can drop an inch off of the od with just a smaller aspect ratio unless you find a tire with one that is 12.5mm smaller. So something like a 295/25/18 which I havent even heard of, but im no tire expert.

Id either fix it the right way or go back to some 17" wheels on the rear.
 
#8 ·
Best to keep the tires less than 1" differential in diameter :yes

Fronts = 25"
rears = 28.4"

Yup.... that's your prob alright :eek: Keep the new rears less than 26" diameter and should have no issues. Best to keep exact, but 26" should be fine.

Jazzer :)
 
#9 ·
ajm said:
Ok so its not a huge issue.

Its throwing off the speedometer and odometer as well. New tires also wont do you much good. I dont see how you can drop an inch off of the od with just a smaller aspect ratio unless you find a tire with one that is 12.5mm smaller. So something like a 295/25/18 which I havent even heard of, but im no tire expert.

Id either fix it the right way or go back to some 17" wheels on the rear.
Click to expand...
not to thread jack...

ajm, i'm running 245/45/17 up front and 315/35/17 and have been told that my abs light is coming from the difference is tire size? is that true??
 
#12 ·
Sorry, pepes.... the tires on o2gtstang are exactly the same size diameter and NOT the cause of ABS issues :no

245/45/17" = 25.7" diameter
315/35/17" = 25.7" diameter

Something else is up here and would suspect a sensor reading the RPM's of a particular wheel.

Jazzer :)
 
#13 ·
If 45mm is the sidewall height of one and 35mm is the sidewall height of the other how is the od not the same?

As said...im no tire expert, i have no interest in that ****, just curious as to how they = out to be the same. Guessing bc didnt exactly calculate height given the aspect ratio?
 
#14 ·
o2gtstang said:
not to thread jack...

ajm, i'm running 245/45/17 up front and 315/35/17 and have been told that my abs light is coming from the difference is tire size? is that true??
Click to expand...
From my personal experience with running skinnies on the front the abs light comes on on me whenever i go anywhere the abs sensor must see that there is less rotating mass and it trips it, cause if i put the 17's back on the abs light never appears:yes
 
#15 ·
This is because the profile hight is a percentage of the width. Because one being 245mm and the other being 315mm, the wider tire with a lower profile just so happens to be the same overal diameter.

Jazzer :)
 
#16 ·
Applehead281 said:
From my personal experience with running skinnies on the front the abs light comes on on me whenever i go anywhere the abs sensor must see that there is less rotating mass and it trips it, cause if i put the 17's back on the abs light never appears:yes
Click to expand...
This is strictly an overall diameter issue and nothing to do with weight. The tires rotational speed is measured by the computer and is compared together. When one, or more, tires are spinning a certain percentage differential, it will trigger this light on your dash.

Jazzer :)
 
#17 ·
Jazzer The Cat said:
This is strictly an overall diameter issue and nothing to do with weight. The tires rotational speed is measured by the computer and is compared together. When one, or more, tires are spinning a certain percentage differential, it will trigger this light on your dash.

Jazzer :)
Click to expand...
Gotcha, cause the fronts are 26X7.5-15 and the backs are 28X8-15's that would explain it, jazzer to the rescue once again LOL!:D
 
#18 ·
Jazzer, i always myself thought it was a sensor reading other then the tire sizes, i didn't know they were the same but i found it funny that would be the case. anyhow my guess was right then and thanks for the confirmation on that going to check sensors and see if the dumb light goes off...i was running slicks and skinnies but haven't for awhile and it's been on ever since
 
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o2gtstang
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