TCM replacement for a 6L80E - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**First c10** · 12-06-2019, 05:36 PM

Hey guys
I started working on my sons 70 again with an LC9/6L80E trans. After the teams rebuild I started having a problem with the very first shift into second each time I start the truck and put into drive. As I reach the shift speed it would like shift into 2nd or maybe even reverse really really hard for a second and then not do it again until I shut the truck off and restarted it then try and drive it again. After the first time it doesn’t do it again and runs/shifts normal. I talked to Mike at Century Transmission which is where I got the rebuild parts and he told me that the TCM may need to be re flashed from a GM dealer or someone with that capability. I took to a shop near me and he tried to reprogram with a new tune and it came back with an error stating it needed to be removed and reflashed on the bench.
Has anyone done this to a 6L80 trans TCM?
I thought I would just buy a rebuilt one but they say they need to be programmed. So I don’t want to buy a new one if I can just have mine reprogrammed.

**First c10** · 12-08-2019, 03:18 AM

Wow nobody has any idea?

prodjay10 · 12-08-2019, 11:29 AM

Maybe someone else can chime but I thought the ecm learning for the transmission had to be reset after a rebuild. Not sure if it's the case with all the chevy electronic transmissions.

**First c10** · 12-09-2019, 02:54 AM

There is a relearn but my problem is with the tcm program according to century transmission

**First c10** · 12-11-2019, 03:48 PM

Has anyone replaced the TCM in there swap? if so what did you have to do with the programming?

rowdy11 · 12-11-2019, 04:27 PM

I didn't replace my TCM or reflash it, but will be watching for this issue because my ECM has been re-flashed and programmed. I also understood that a new or reflashed TCM needed to go through a "re-learn."

12-06-2019, 05:36 PM	#1
First c10 Senior Member Join Date: Dec 2012 Location: Los Banos CA Posts: 2,705	TCM replacement for a 6L80E Hey guys I started working on my sons 70 again with an LC9/6L80E trans. After the teams rebuild I started having a problem with the very first shift into second each time I start the truck and put into drive. As I reach the shift speed it would like shift into 2nd or maybe even reverse really really hard for a second and then not do it again until I shut the truck off and restarted it then try and drive it again. After the first time it doesn’t do it again and runs/shifts normal. I talked to Mike at Century Transmission which is where I got the rebuild parts and he told me that the TCM may need to be re flashed from a GM dealer or someone with that capability. I took to a shop near me and he tried to reprogram with a new tune and it came back with an error stating it needed to be removed and reflashed on the bench. Has anyone done this to a 6L80 trans TCM? I thought I would just buy a rebuilt one but they say they need to be programmed. So I don’t want to buy a new one if I can just have mine reprogrammed. __________________ 1956 Chevy Bel Air 2 door 1956 Chevy 210 4 Door 1970 K20 LWB project the Hulk build w/Supercharged 4.8L-ly2/4L60E HULK BUILD 1970 C10 Yellow/White Deluxe LWB w/ 5.3L-LC9/6L80E 1968 K10 LWB Dark green my son calls it "THE HULK Jr"HULK JR SOLD GO GO!!!

12-08-2019, 03:18 AM	#2
First c10 Senior Member Join Date: Dec 2012 Location: Los Banos CA Posts: 2,705	Re: TCM replacement for a 6L80E Wow nobody has any idea? __________________ 1956 Chevy Bel Air 2 door 1956 Chevy 210 4 Door 1970 K20 LWB project the Hulk build w/Supercharged 4.8L-ly2/4L60E HULK BUILD 1970 C10 Yellow/White Deluxe LWB w/ 5.3L-LC9/6L80E 1968 K10 LWB Dark green my son calls it "THE HULK Jr"HULK JR SOLD GO GO!!!

12-08-2019, 11:29 AM	#3
prodjay10 Registered User Join Date: Jun 2016 Location: Phoenix AZ Posts: 429	Re: TCM replacement for a 6L80E Maybe someone else can chime but I thought the ecm learning for the transmission had to be reset after a rebuild. Not sure if it's the case with all the chevy electronic transmissions.

12-09-2019, 02:54 AM	#4
First c10 Senior Member Join Date: Dec 2012 Location: Los Banos CA Posts: 2,705	Re: TCM replacement for a 6L80E There is a relearn but my problem is with the tcm program according to century transmission __________________ 1956 Chevy Bel Air 2 door 1956 Chevy 210 4 Door 1970 K20 LWB project the Hulk build w/Supercharged 4.8L-ly2/4L60E HULK BUILD 1970 C10 Yellow/White Deluxe LWB w/ 5.3L-LC9/6L80E 1968 K10 LWB Dark green my son calls it "THE HULK Jr"HULK JR SOLD GO GO!!!

12-11-2019, 03:48 PM	#5
First c10 Senior Member Join Date: Dec 2012 Location: Los Banos CA Posts: 2,705	Re: TCM replacement for a 6L80E Has anyone replaced the TCM in there swap? if so what did you have to do with the programming? __________________ 1956 Chevy Bel Air 2 door 1956 Chevy 210 4 Door 1970 K20 LWB project the Hulk build w/Supercharged 4.8L-ly2/4L60E HULK BUILD 1970 C10 Yellow/White Deluxe LWB w/ 5.3L-LC9/6L80E 1968 K10 LWB Dark green my son calls it "THE HULK Jr"HULK JR SOLD GO GO!!!

12-11-2019, 04:27 PM	#6
rowdy11 Registered User Join Date: Nov 2017 Location: SLC Utah Posts: 210	Re: TCM replacement for a 6L80E I didn't replace my TCM or reflash it, but will be watching for this issue because my ECM has been re-flashed and programmed. I also understood that a new or reflashed TCM needed to go through a "re-learn." __________________ 1970 K10 Shortbed LS L96 6L90 Follow the entire mess below! Lola: My Moon Shot



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