6L80E fast learn not working on 2017 GMC Sierra

[hirdlej]

I'm trying for the first time to perform the fast learn on a 2017 GMC Sierra with a 6L80E. I had the trans temp up to 185, set the parking break, truck idling in Park. Went into the scanner and clicked on the fast learn while holding the brake pedal down. Nothing happens. What am I missing? Or because of the TCM in these new trucks does the fast learn procedure not work? Any help or walk-through advice is appreciated.

[brandonleg]

Having the same issue on my 2018 2500hd (6l90e). I also can?t access it through ACDelco SPS / GDS using my mongoose interface, it's just not even listed as an option where it should be, so I?m wondering if it?s a GM thing. I?ve scoured all the GM literature I can find, can?t find where they talk about deleting it, or changing anything, though.

I've had tranny temp up to 200, HPT said "too cold". Around 205 or 210 it said too hot.

Worked fine on my 2015 8l90e, so I don't know...

[hirdlej]

Interesting...... I can't even get it to acknowledge anything. Not even a "too cold" message. Have you tried setting the parking brake and then holding the brake pedal down before you stasrt on yours Brandon?

[brandonleg]

Yep, I've tried that. Also tried starting the procedure while in drive. Went back and re-read posts and stickies here just to make sure I wasn't losing my mind.

I believe the parking brake is more of a safety thing than an actual pre-requisite for the test, but since GM lists it as a step in some of their documentation, I do set it.

I don't have the factory service manual for the 2018, I'm curious what it says. The Gm literature you buy a subscription for on acdelco's site doesn't have the fast learn procedure in it, though, that I could find.