07 4L60 1-2 shift issue

[Rick P]

I have a weird issue going on with a friends truck and this only happens when you put it in park then drive or reverse then drive, when i go to take off and when it's time to shift 1-2 it hangs in neutral or in between gears no matter what you do with the throttle, after about ten seconds it will be fine forever until you put it in park again. Every single electronic part has been changed with new GM OEM parts including throttle pedal, i'm completely stumped on this one. Other than the initial fit it gives the trans works fine.

[TheMechanic]

There have been some software updates to these trans issues. Does not mean that is your particular situation but there are throttle progression and second gear start issues among others. I suggest you return to stock programming, check for factory/dealer software updates. If there are none return your tune. If there is have them flash it, then you will have to re-download your NEW STOCK file and modify it. Dump/archive your old files so you don't mistakenly reintroduce the errors back into the corrected programming.

[Rick P]

Thank you tomorrow i'll connect to it with MDI and TIS and see if there is an update to it.