2012 silverado, e38+t42+4l80... help

Hey guys, ive recently finished rebuilding/upgrading a 4l80, and im finally starting down the path of getting the t42+4l80 to work in place of the original 6l80/t43.

ive built a harness that connects the t42/4l80/range sensor to the original 6l80 wiring.

some things that i know:
2012 silverado 1500 LT 1GCRKSE77CZ199955 - e38 - os 12647991
not sure of exact t42 original, but it has OS 24235341

it looks like theres very few 2010+ 4l80 options. is using a 4l60 tune to control the 80 a valid strategy?

From what ive read so far im led to believe that: ill need to find a 2010+ os that will let my t42 work with my 2012 e38. but ive read a few 2009 van tunes potentially work?
or
ill need to swap both of them for 08 but not 09 files?

i dont have hardware to flash either, but id rather have the tools than go to the dealer a bunch of times. is there an accepted best aftermarket tool like the vcx nano?

If anyone lives near Indianapolis and feels like helping out hit me up, ill buy beer pizza gas whatever and show you around a shop filled with badass gt350s/gt500s.

Im sure ive left some pertinent information out, let me know what else i need!

Thanks,

Matt

The swap harness with a 60E OS is your best bet if this is not a swap vehicle and you want the PRNDL and other doo-dads to still work.

Yes there are '09-up 80E OSes, from the Express vans. Look for files with the 127lb injector flow rate limit; those are 'late', the ones with 63lb limit are 'early'. So, the Express OS will work with your ECM and your trans, but maybe not the rest of the truck.

edit: You can fully program (change to a totally different OS) T42s (and T43s) with HP Tuners & Write Entire. It's the Gen 4 ECM that can't be fully flashed.

well id definitely prefer to keep my doodads.
ill start looking for an appropriate 60E os, are there any caveats to running the 4l80 on the 60e os? looks like there used to be issued with the tcc unlocking on pedal lift that an update fixed, and i know the 60 has that 3-2 solenoid... but poking around in the t42 with hptuners i see an option where you can specify whether a 3-2 is installed or not.

when you say swap vehicle what does that imply? swapped ecu as well?

thanks for that edit, sounds like a 60e os helps avoid not having to mess with the ecm os. big win

https://www.pcmofnc.com/product/pcm-...rsion-harness/

By swap vehicle, I mean it's an engine and ECM from a 2012 Silverado but transplanted into something else that doesn't have all the other Silverado modules on the bus. If it's not a swap, then you have all the rest of the truck to worry about.

Stock 2009 Express/4L80E files are in the repository. TCM OS is 24243356. You can try it first (TCM only), but it will cost you 2 credits to license the Express file before it will let you write it.

oh that makes sense. yep, its a full bus silverado.

do you know any of the particulars of that swap harness? currently i have the 80 wired up to the tcm like it was a 80 tune, but im not afraid to swap stuff around.

That adapter uses 60E wiring/pinning and a 60E OS.

PCMofNC dude-> https://forum.hptuners.com/member.php?5378-Alvin

Ok status update, finally got to work on the truck again.

currently i have the 09 express written to the tcm. dash still says prndM, but it indicates correctly with the range selector, so i assume most of my wiring is complete. currently not getting a start though. looking at vcm scanner, i can see that turning the key results in "Crank Request" flipping from No to Yes, but "Starter Relay" always says off.

jumped the starter and it started and ran fine on the lift.

so a few things im confused about that maybe someone else knows already. my 6l80 connector had: bat, ign, gnd, accy voltage, pnp switch, and two sets of CAN wires. Those 7 wires are the only connections between the Truck and Tcm/Trans/Range/ etc. I currently have the pnp hooked up to the 4l80 range sensors pnp output (pin 9), and ign12v goes to 11 and 12.

Attachment 151961

I researched and made the harness myself, i was careful and made connections that made sense based on diagrams, some posts, and the factory naming of the circuits, but its entirely plausible i missed something and need to change some things.
i can post my wiring here if anyone wants to look at it. its in a spreadsheet though so its not pretty.

I saw your other reply BlindSquirrel and a 2012 4l60 OS is next up on the list, but i wanted to give the 09 express file its fair shake before i gave up.

Hello I'm kinda in the same situation would you mind providing your wiring you did ? I can't find any wiring information that corresponds with my current plug configuration. Thank you

sure i can post it up, its currently still a work in progress though, so things might change to get it working

Attachment 151976

quick update, the truck starts if you give the original 6l80 pnp pin gnd instead of 12v, so thats an easy enough adjustment to make in the harness.

Attachment 151990 Attachment 151991

That's an easy fix, relocate the pin in 9 to 3, excellent thank you. looks like i didnt need to bring power to the range switch at all for my truck.

i wonder if the tcm is gonna be able to grab oss from CAN or if this express tune would require me to add an oss.

The dashed outline around a component indicates that it is not showing ALL the pins going to that component/connector. You need your own diagrams to be doing stuff like this. DelcoTDS, alldatadiy, etc.

Youre absolutely right, i have access to the ford stuff for work, but no GM. I paid for alldata at the start of the project, but i let it expire without taking screenshots and i was too stubborn to buy another month.

I have a 2012 E38 and T42 with a 4L80 swapped into a 2000 Camaro. The 2012 harness came with the 6L80 plug. I removed the wiring for the 6L80 and used a 2008 donor transmission wiring harness that had 4L60 plug and wiring. I didn't use the swap harness between the 60 and 80, I swapped some pins around and plugged the 60 plug directly into the 80 trans receptacle.
If you take the 60 plug, look at the pins with the notch at the top---the top row of pins is 4 across, 2nd row is 6 pins, 3rd row is 6 pins, 4th row is 4 pins (hope that's the plug that you have) OK, Clockwise looking at the plug at the 1:00 o'clock position, or 4th pin in row 1, That is pin A, next down is at the end of row 2 and is pin E---Pin E is 12 volts---next is end of row 3, pin L. end of row 4 is pin T. At the other end of row 4 is pin V, row 3 pin S, row 2 pin K, row 1 pin D. There is a Brown wire that has a pin also, locate that one by looking at the wire bundle and tagging it. That's pin U. Now, remove white wire and pin S---remove tan/blk pin T---remove Lt blue pin V--remove orange pin K. Pin K and pin V go to the ISS plug on top of the trans. Move brown wire pin U to pin S position. In the TCM connector remove white #14 and tan black #25. Move pin #45 to pin 26 position. On your E38 computer BLACK plug run your brake switch signal to pin 9. (You may already have this in the harness, I don't know. It's to release the converter lockup.)

Back at it again
ive got the 4l60 os in now, but not getting vss
4l60 trucks have the vss in the tcase wired to the tcm, currently mine is still wired to ecu. running the vss to the tcm is likely the next step, im just making sure we dont already have that covered with a workaround in the software.

heres an updated wiring pinout for anyone following along;
Attachment 154574

An auto trans ECM OS cannot and never will be able to read the VSS on the same ECM pins that a manual trans ECM OS uses. It must go to the TCM, which then sends VSS to the ECM over CAN. An auto trans ECM cannot get a VSS reading in any way other than over CAN from a TCM.

thanks blind squirrel, i still have the original 6l80/5.3 ecm OS 12647991 loaded which uses the VSS via pins 72 and 73.

so far ive only been changing the OS on the tcm, and using the drop downs to make changes to my original ecm OS. Based on the language in the swap harness listing ("Cruise control, gear indicator, & factory transmission temperature gauge work with this swap! No reprogramming of ECM or BCM required!") ive been hesitant to make too many changes to the ecm. obviously i didnt purchase the kit though, so i dont know what other steps must be taken beyond the harness install.

my next planned step is to wire the vss into the tcm and try again with my os. I dont feel informed enough yet to guarantee avoiding a bricked ecm.

6L80 is an auto trans, the ECM OS to work with any auto trans will not read a hard-wired VSS. It must come in over CAN, from a TCM, whether that TCM is a T43 or T42.

Attachment 154584

it looks like this diagram is saying that my vss, mounted to the output of my transfer case, is hardwired to my ecu from the factory.
i havent actually traced the wire in real life yet, though.

Attachment 154585

i dont care about being right, btw, im just confused.

What is the Output Speed Sensor for, then? Why is there an ISS & OSS wired direct to the TCM, and that extra 4WD-only thing they're calling 'VSS'?

My wild-ass guess is that that speed is just sent directly to the Instrument Cluster so the hi-lo of the transfer case is doesn't matterfor showing vehicle speed.

Did this ECM start out in a 4WD?

re: Blind squirrel. what you said before about the oss wired directly to the tcm on the t43. that means my truck as it was built had iss, oss, and post transfer case vss.
looking at the 4l60 builds, they have iss, no oss, and they use the post transfer case vss with the t42. im also noticing a replicated tos hardwired from the t42 to the e38 in the diagrams. some of the options in the vcm editor lead me to believe this might be done via can.

Attachment 154589

then again i could just be seeing what i want to see

re: gtstorey
yep, the whole project is being done in the original truck, 6l80+t43 swapped out for 4l80+t42

I think were finally getting somewhere

i was getting a p0716 iss code along with max line pressure, but iss rpm looked like it was solid, so i tried disabling the p0717 diag which seems to have done the trick

also getting a p2160, but it doesnt seem to be causing other issues yet. im assuming its cause the vss sensor has now been hijacked from the ecm for the TCM. i imagine resolving this will require running another wire from the tcm to the ecm for the replicated tos.

shifts are very stout at part throttle for now, but i havent started messing with the shift times and pressures yet.

i still havent messed with changing my e38 OS yet. its been working well enough to test out the tcm/4l80 so far but id eventually like it to all be right.
is the accepted answer.

if it helps at all ive attached the tune

Attachment 155320