How do you control a 6L80E or newer? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

davepl · 03-25-2017, 01:07 PM

My understanding is that the newer trans like the 6L80E have their control module internal, so that normally the engine computer communicates with, but does not "control", the transmission.

If you were going to put a 6L80E in one of our trucks behind a carb'd big block, for example, what could you use as a standalone box to get it running?

I have a 4L80E with a TCI box that controls it, but I think it's different with these later transmissions... I just don't really know.

BR3W CITY · 03-25-2017, 07:14 PM

6l80e's run off of a T43 ecm IIRC. The OS type and year needs to match the ECM.
I don't know if there is any aftermarket stand alone that will control them.

The module is in the trans pan and runs off of CAN protocol, so any device attempting to control it would need to also link via the CAN. The alternative (and this is something I've only read about and never actually seen in person), is to drop the pan and bypass or replace the TCM. Its just solenoids and switches like most any other auto, so it COULD be made to run off something like MegaShift or another aftermarket TCM...but it would be a serious effort.

Big Port Jimmy 6 · 03-25-2017, 09:29 PM

Megashift now that's an interesting idea. I wonder how the clutch to clutch shifts complicate things. Pops bought a truck with the 6l80. And I love the deep overdrive.

davepl · 03-26-2017, 11:43 AM

Yup, I know the basics of how it works when the vehicle's engine ECM is present, but how would you make it work when it's not?

I wonder if it requires a "simulator" of sorts to tell it CAN bus parameters that it's watching for. For example it might want Engine RPM, so somewhere in your magic box you'd need a circuit that measures RPM and outputs it as a CAN packet on a wire that the trans listens to, that sort of thing.

All in all it should be a lot easier than building a standalone controller for the 4L80E where you're doing ALL of the heavy lifting, code-wise. Then again if it's so easy, where are they? :-)

BR3W CITY · 03-26-2017, 06:17 PM

Keep an extra ECM wired in the glovebox? lol

03-25-2017, 01:07 PM	#1
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	How do you control a 6L80E or newer? My understanding is that the newer trans like the 6L80E have their control module internal, so that normally the engine computer communicates with, but does not "control", the transmission. If you were going to put a 6L80E in one of our trucks behind a carb'd big block, for example, what could you use as a standalone box to get it running? I have a 4L80E with a TCI box that controls it, but I think it's different with these later transmissions... I just don't really know. __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

03-25-2017, 07:14 PM	#2
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: How do you control a 6L80E or newer? 6l80e's run off of a T43 ecm IIRC. The OS type and year needs to match the ECM. I don't know if there is any aftermarket stand alone that will control them. The module is in the trans pan and runs off of CAN protocol, so any device attempting to control it would need to also link via the CAN. The alternative (and this is something I've only read about and never actually seen in person), is to drop the pan and bypass or replace the TCM. Its just solenoids and switches like most any other auto, so it COULD be made to run off something like MegaShift or another aftermarket TCM...but it would be a serious effort. __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

03-25-2017, 09:29 PM	#3
Big Port Jimmy 6 Addicted to Rust Join Date: Dec 2009 Location: Abbeville SC Posts: 1,030	Re: How do you control a 6L80E or newer? Megashift now that's an interesting idea. I wonder how the clutch to clutch shifts complicate things. Pops bought a truck with the 6l80. And I love the deep overdrive. __________________ Current trucks: (48 GMC100 320 inliner) Gone (48 Suburban in pieces) Sold 87 GMC CCSB 5.3 4l60E Daily Driver ECTA National record holder XO/PP We never really grow up, we just learn how to act in public.

03-26-2017, 11:43 AM	#4
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: How do you control a 6L80E or newer? Yup, I know the basics of how it works when the vehicle's engine ECM is present, but how would you make it work when it's not? I wonder if it requires a "simulator" of sorts to tell it CAN bus parameters that it's watching for. For example it might want Engine RPM, so somewhere in your magic box you'd need a circuit that measures RPM and outputs it as a CAN packet on a wire that the trans listens to, that sort of thing. All in all it should be a lot easier than building a standalone controller for the 4L80E where you're doing ALL of the heavy lifting, code-wise. Then again if it's so easy, where are they? :-) __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible Last edited by davepl; 03-26-2017 at 02:09 PM.

03-26-2017, 06:17 PM	#5
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: How do you control a 6L80E or newer? Keep an extra ECM wired in the glovebox? lol __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD



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