This evening driving home the transmission started to act up. I stopped and shut it down. It started up fine but now I only have first and second gear.... And once it shifts to second it will abruptly downshift to first until I hold it for a minute. Does not have 345or6. Any help is appreciated thanks

 

It's possible it's an electronic issue. These 6L80's no longer use one way clutches, it's just a clutch to clutch system with the TCM controlling pretty much everything.

Do you still have a warranty??

 

It just hit 20k

 

what year? 4x4 ? engine ? mods? any other info

 

try unplugging you battery for a few minutes...may sound stupid but i only had 1st gear and i stopped at the gas station unplugged the battery and it was back to normal...i was told it went into a safe mode

 

2014 Sierra 5.3, stall tune gear lts

 

Modified yikes,how many miles on mods? has it been spot on till now ? Jake75 said disconnect battery for a bit,I agree.Next thing will be go see your tuner.It could have codes

 

In for updates

 

mine went into safe mode again last night at the track (stayed on 2 step too long) went down the 1/4 in 1st gear...got parked and disconnected battery everyting went back to normal.

 

Sorry to hi-jack, but you made 600/638 with heads/cam?


How is the transmission holding up to it?