I thought I had this figured out but its not working on a truck so I want to confirm what is needed to add this feature into the ECM.

https://www.gmupfitter.com/publicat/...82a_081412.pdf


The customer got the update to both the ECM and BCM and it was working. I flashed in my original file without the fast idle but changed the GMLAN Fast Idle to enable (all I figured I had to do) however after the flash the fast idle ceased to work.

The truck I am working with is a 2015 with a 0477 OS.


Thanks in Advance.