HPTuners NNBS tire change=brake and ABS light
May 23, 2017 | 09:26 PM
#22
Because I've changed tire sizes on hundreds of NNBS trucks. I do this professionally FWIW. And unless you are trying to put in a 35" tall tire size I don't have this problem. I can fix his problem. Sorry he can't provide me with the information I need. And there is no need to use a HPT beta version on a 07 NNBS truck. There is nothing he can do with that beta version on that model truck that I can't do with V2.24. Perhaps it is a bug that is causing that problem with a 31.5" tire.
May 23, 2017 | 09:30 PM
#23
Jun 5, 2017 | 09:07 AM
#27
Jun 11, 2017 | 07:24 AM
#28
Staging Lane
Joined: Jan 2012
Posts: 70
Likes: 3
From: CT
@mcfarland,
Glad the calcs in this worksheet worked for you. I can't explain why the HPTuners wizard does not work, I just know I've read posts over on their forum and done lots of testing/validation that the wizard does not work on truck E38 speed calcs. I believe they mention that if they "fix" the wizard for one group of E38 OS's, it breaks for the others. Apparently GM has changed the way they calculate speed a half dozen or so times throughout the E38 timeframe.
For others who may find it useful, I've attached the sheet below. Its pretty self explanatory and basically all it does is tries to keep the up/down scaling such that the front tires (non-driven) in the ABS module in sync with the rears so that the EBCM doesn't freak out and throw a code (C0245 with brake light + ABS light). The nice thing about the sheet is you can run different size fronts than rears and it will weight the PCM 128K signal accordingly.
The latest version of HPTuners, 3.6.x has added parameters to the tune; Driven wheel circumference and non-driven wheel circumference. I have played around with these PIDs to no avail and cannot explain how they play into the speed calc algorithm so I find it best to just leave those stock no matter what. If I figure out what they are doing I'll update my workbook and post here but for now this seems to work just fine without it.
Note: Please keep in mind that since you are adjusting these settings manually, you'll need to adjust your trans settings manually as well. You may be able to use the wizard for that or you could use the BlueCat BC_Trans tools which is a really nice free tool.
Glad the calcs in this worksheet worked for you. I can't explain why the HPTuners wizard does not work, I just know I've read posts over on their forum and done lots of testing/validation that the wizard does not work on truck E38 speed calcs. I believe they mention that if they "fix" the wizard for one group of E38 OS's, it breaks for the others. Apparently GM has changed the way they calculate speed a half dozen or so times throughout the E38 timeframe.
For others who may find it useful, I've attached the sheet below. Its pretty self explanatory and basically all it does is tries to keep the up/down scaling such that the front tires (non-driven) in the ABS module in sync with the rears so that the EBCM doesn't freak out and throw a code (C0245 with brake light + ABS light). The nice thing about the sheet is you can run different size fronts than rears and it will weight the PCM 128K signal accordingly.
The latest version of HPTuners, 3.6.x has added parameters to the tune; Driven wheel circumference and non-driven wheel circumference. I have played around with these PIDs to no avail and cannot explain how they play into the speed calc algorithm so I find it best to just leave those stock no matter what. If I figure out what they are doing I'll update my workbook and post here but for now this seems to work just fine without it.
Note: Please keep in mind that since you are adjusting these settings manually, you'll need to adjust your trans settings manually as well. You may be able to use the wizard for that or you could use the BlueCat BC_Trans tools which is a really nice free tool.
Jun 30, 2017 | 08:17 AM
#30