2008 silverado gear change ABS light

[grandam75]

Hello,
Spent half day testing differnt settings and problem not solved. 2008 3500HD (duramax/allison), gear ratio changed from 4.10 to 4.88 and ABS + brake light comes on at 30mph. Tried the gear/tire wizard, tried keeping the ECM side stock as well as some manually calculated values but no luck. Calibration is strage from factory with 3.73:1 in ECM and 4.10:1 in TCM. Attaching file, any help would be great. I have only until tomorrow to solve it and then vehicle will be far away.3500Dmaxstock.hpt

[Jon S.]

Plenty of threads on the internet about this topic ... if the gear ratio change is not a huge jump, the ABS Module will sometimes "sync" ... however, often the ABS Module (EBCM) needs to also be reprogrammed - HP Tuners cannot help you with that task.

[grandam75]

Plenty of threads on the internet about this topic ... if the gear ratio change is not a huge jump, the ABS Module will sometimes "sync" ... however, often the ABS Module (EBCM) needs to also be reprogrammed - HP Tuners cannot help you with that task.

Thank you for info. Yes, I found some info about similar cases but no real clear solution. Tech 2 would be able to fix the EBCM?

[grandam75]

So made another attempt today and finally got the abs light to stay off. Solution in this case, set the gear ratio change and transmission tables. Increase the vss tire rev under sensor calibration until the light stays off (same as reducing tire diameter). Speedo is about 10% off because of this but owner was ok with that. If I had more time I would play with the settings in ECM vs TCM independetly to try and get the speedo corrected. Would be intersting to know which parameters are reported to the EBCM vs speedo cluster.