Brake abs light

Chevy1925

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I'm confused.... So anything above 35" tires will trigger the abs light??? If so, then why isn't my abs light on? I have efi live and my tires are badass

no, any value entered in the speedo correction of 34.25 and up will trigger the light. keep up sweet cheeks :D
 

Chevy1925

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No my edge race evo did tune the ecm and my speedo.

couldnt tell you then why edge didnt set it then. none of us know how they program any of their stuff. For EFI Live, both steve and i have explained why and unless you can get a scanner that can pull the codes and you can tell me if the e-brake light is also on with the ABS light, there aint much else you can do till you hear back from tony.
 

diesel53

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Okay I appreciate the help guys. Ill try Tony again.

Ebrake light (red one) is on as well...
 

Too Many Projects

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I just posted about this same issue. I had 37's with stock gears & the speedo read correct with EFI tuning & no issues. I went up to 40" tires & 4.56 gears, now I get the ABS & parking brake lights (also disables the parking sensors & gives "service trailer brake wiring" message).
As far as I know, the issue is that EFI adjusts the speedo signal that is read off the rear tires (in the T-case I believe) & your ABS is picked up off of the front wheels which are still set to the stock tire size (can't be changed with EFI). These two signals can be off from each other up to a certain percentage before it will trip the ABS light. This is why you can go up to 34.25" before it comes on, it keeps it within that percentage.
However I thought you could up the tire size in the ABS module with a Tech 2 to allow you to go a little bit bigger? I believe that's even what the sticky on this site states?
I tried to change the ABS setting in the EBCM with a Tech 2 but apperently it doesn't allow you to, atleast on the NBS trucks?
 

Chevy1925

don't know sh!t about IFS
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I just posted about this same issue. I had 37's with stock gears & the speedo read correct with EFI tuning & no issues. I went up to 40" tires & 4.56 gears, now I get the ABS & parking brake lights (also disables the parking sensors & gives "service trailer brake wiring" message).
As far as I know, the issue is that EFI adjusts the speedo signal that is read off the rear tires (in the T-case I believe) & your ABS is picked up off of the front wheels which are still set to the stock tire size (can't be changed with EFI). These two signals can be off from each other up to a certain percentage before it will trip the ABS light. This is why you can go up to 34.25" before it comes on, it keeps it within that percentage.
However I thought you could up the tire size in the ABS module with a Tech 2 to allow you to go a little bit bigger? I believe that's even what the sticky on this site states?
I tried to change the ABS setting in the EBCM with a Tech 2 but apperently it doesn't allow you to, atleast on the NBS trucks?

Your problem is different than the one the OP is asking about. You changed gearing which adds a whole nother realm in. You have your thread you started,no need to keep posting the same stuff over and over in other threads that deal with abs
 

Too Many Projects

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Your problem is different than the one the OP is asking about. You changed gearing which adds a whole nother realm in. You have your thread you started,no need to keep posting the same stuff over and over in other threads that deal with abs

Wow...I was in no way trying to overtake the op's thread. I thought some of the information I have learned in the process might be helpful to him. Maybe I rambled on a little too much.
...and believe me, I agree about not reposting over & over again on the same subject, I just realized that a sticky that's been at the top of a page for a couple years doesn't really get any traffic.
 

Chevy1925

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I put the tire size in requested, It is an easy fix, but the speedo will be off.

I have always recalibrated the BCM with my TECH2 on local trucks........apparently GM took another option away on the NBS trucks.

:(

There ya go diesel53, tony has got ya :D
 

Chevy1925

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Before everyone starts postin in here thinkin they have the same issue, think of the ABS light this way. Its the same thing as a Check Engine Light but for the ABS system. if the light comes on, pull the codes if at all possible otherwise we are chasing issues without a real starting point. Only a few key things like "the light came on after i changed my tire size" would point us to a tune issue.

Low brake fluid

That causes ONLY the ebrake light to come on. if both come on from low brake fluid, you got some really crappy brakes cause there is air in the ABS modual at that point.
 

JoshH

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You need to check it with a scan tool that can pull ABS codes.