05 Colorado ZQ8 tuning issue

[ZNA03]

This weekend I went to tune a local member of a colorado forum i belong to and everything went fine, the download of the stock file and the writing of the new file went smooth. He couldn't immediately drive the truck since he was stuck at work, anyways i assumed everything was fine because its the same safe tune i do on everyones truck i've done.

Truck is a 2005 Colorado ZQ8, Manual, Lifted, 3.42 gears (TRAC CONTROL and Locking Diff), 33's (32.7), K&N intake, Magnaflow exhaust.


Issue: After tuning the truck will show "LOW TRAC" in the Drivers Info Center but will not pull power or effect drivability. The truck drives and shifts fine but the warning shows up when in motion and goes off when stopped at a light and idling and re-appears again once the truck goes back into motion. This happens when the T/C button on the dash is ON (Traction control system active)

Also with the T/C button OFF, the ABS FAULT warning shows up in the DIC about 8-10 minutes into driving. So either way there is an issue with something in the computers.



Here's what i've tried and where i'm at right now...

1) I tried turning the truck back to stock to see if anything is broken mechanically or if it was in-fact the tune I loaded. We drove around the lot with no warnings or problems.

2) I loaded the tune with only the tire size adjusted to make sure it wasn't anything else I edited or changed in my tuning process, still have the error so it's happening when I do the commit from changing the tire height from the stock ZQ8 wheel which is on the stock program (25.7 I believe) to the new wheel and tire combo (32.7) 33 inch tires.


When we disable the traction control on the truck using the button on the dash the warning does not appear (duh i know) even with the adjusted tire size and changed I made to the program but just for arguments sake we tried it.




So thats where i'm at on this... i've spoke with a couple people and they think it's a possible disagreement between the BCM and PCM which is causing the errors to occur but not effect the vehicle besides put up the warning on the DIC.

Thanks for any help you leave in advance....

-Zach

[EC_Tune]

Could also be an ABS issue. I think they use a 3-wheel ABS system like their fullsize brethern. Since you recalibrated the trans (hence the 3rd wheel) the differential between front and rear is probably making the stability/ABS system unhappy. You will probably have to change the tire size in the ABS with a Tech2.

[ZNA03]

I see... in other words, no dice...

[EC_Tune]

Or if you wanted to, you could put the trans/revs/mile back to stock and leave the Speedo calibrated correctly with the current VSS PPM.

The trans shift points would be a little wacky but if you don't have access to a Tech2 that is your only option.

EC

[ZNA03]

Its a manual... would the shift points even make a difference? Im assuming they wouldnt.

[EC_Tune]

No they wont. As you get to pick your own.
So just get the speedo section VSS PPM correct and put the trans revs/mile back to stock. Should fix it.

[jackedupcanyon]

Hate to bring up a thread that is 2 years, 4 months and 3 days old but did this work for the original poster? Doubt he is even around any more but I had the same issue this weekend. Drove 309 miles one way to tune a guy over the weekend. Made it back no issues then the next day I get word he is having ABS Fault issues. F'n great. Call in sick to work the next day, drive back up there and spend the entire day trying to either rule that he had faulty sensors or his previous tuner had somehow screwed up his tune. He also had a manual so I tried just changing the values on the speedo screen.....no workie. Tried calculating them, no workie. Even tried calculating the values and adding the same % differences in the original tune, still no workie. Only thing that works is to use the stock tire size or a small tire size change. The best I can figure is that the ABS module can only tolerate a max tire size from the stock (25.7) size and 7" larger is beyond that tolerance. Anyone know what the max tire size the ABS modulate can handle with a stock tire size of 25.7" Also does anyone have access to a tech2 in the KY,TN or GA area?

[camaro1]

the abs module has its own tire size calibration that can be programmed with a gm tech 2,,, the abs module can only see so many % diff from the pcm calibrated speed and the abs wheel speed sensors before it sets a code, i know this is true for the silverado's and im sure the colorado abs system works simular

[jackedupcanyon]

Yep, that is what I figured. Now if we can just someone with a GM tech2 that we can take it to. The truck owner prefers to not just blindly take it to a dealership and would rather pay someone at the back door to have the correction made. Thanks for the reply confirmation.

[gabe74gt]

I have the same magnaflow too and love it, you can usually get a used one on ebay or cragislist. I wanted a valid warranty so I got it here. Magnaflow 49164. Also some of the forum sponsors selling magnaflow usually have a sale going on. Either way its a great cat, sounds great, and very easy to install.

[wpage]

Soo was there a solutions to the problem?

[Bill@HPTuners]

Soo was there a solutions to the problem?

Calibrate ABS module more than likely, its not a pcm issue.

[ElecTech]

Bill,

You may wan't to look into this perameter to see if it may help. I see it in most of the "LS" based calibrations, especially the truck calibrations.

[Bill@HPTuners]

Thanks ElecTech I'm going to look into this a bit further.

[Bill@HPTuners]

Doesn't look like its there in P12's.

[supermodulation]

I just did a gear swap from 3.73's to 4.10's on a 4x4 and I had the same problem "ABS FAULT". Tire size was the same. I'm going to attempt to adjust it back to 3.73 to see if the idiot light goes out.


All help is appreciated!


Thanks,
James