New Torque convertor now ECM Wont Communicate

[68jay]

Hoping someone can shed some new light...Long Story short I have a 2017 Tahoe, transmission started slipping in 1-3 gear, took it out and apart. Everything I checked was in good shape (ie Clutchs/bearings etc.) I replaced the Torque Converter and reinstalled everything back in..

As always I had the battery disconnected in all this but when I hooked it back up seemed to be at only 5 volts..not sure how..recharged and tested battery everything was fine..

Truck dash lights up gives me a bunch of warnings about steering, stabilizer etc but will not start and then gives me a warning that its "not in park"? Checked everything to make sure including opening up the pan and physically checking and including replacing the "Shift Indicator switch" on the TECHM but still gives me the "Action Notice".

Hooked up my scanner and tells me "Error" and cannot even read my ECM (Fuses etc all fine)..I have chased my tail with double checking everything but have been defeated.

Any new ideas would be helpful!

 

[NickTransmissions]

Hoping someone can shed some new light...Long Story short I have a 2017 Tahoe, transmission started slipping in 1-3 gear, took it out and apart. Everything I checked was in good shape (ie Clutchs/bearings etc.) I replaced the Torque Converter and reinstalled everything back in..

As always I had the battery disconnected in all this but when I hooked it back up seemed to be at only 5 volts..not sure how..recharged and tested battery everything was fine..

Truck dash lights up gives me a bunch of warnings about steering, stabilizer etc but will not start and then gives me a warning that its "not in park"? Checked everything to make sure including opening up the pan and physically checking and including replacing the "Shift Indicator switch" on the TECHM but still gives me the "Action Notice".

Hooked up my scanner and tells me "Error" and cannot even read my ECM (Fuses etc all fine)..I have chased my tail with double checking everything but have been defeated.

Any new ideas would be helpful!

Idea #1 - change your thread title, put something that indicates your specific problem

Idea #2 - Perform a Fast adapt relearn - must be done before you attempt to drive it.

Idea #3 - Read through my thread on these transmissions, you may find your answers, including your IMS concern, there.

GM 6L80 Transmission Information Thread

Hi All, Since so many of us own at least one Tahoe or Yukon equipped with a 6L80, I figured I'd start an all-encompassing transmission thread with videos, links and other information as it relates to the 6L80/90 transmissions. I'll get it going with a tear down and inspection video and go from...

www.tahoeyukonforum.com

 

[OR VietVet]

Well, since it sounds like you did not have the problem before the work, you gotta do your due diligence and reinspect the work and connections you did.

 

[68jay]

Idea #1 - change your thread title, put something that indicates your specific problem

Idea #2 - Perform a Fast adapt relearn - must be done before you attempt to drive it.

Idea #3 - Read through my thread on these transmissions, you may find your answers, including your IMS concern, there.

GM 6L80 Transmission Information Thread

Hi All, Since so many of us own at least one Tahoe or Yukon equipped with a 6L80, I figured I'd start an all-encompassing transmission thread with videos, links and other information as it relates to the 6L80/90 transmissions. I'll get it going with a tear down and inspection video and go from...

www.tahoeyukonforum.com

Thanks I will read through...and Edited my title..

 

[91RS]

Make sure the transmission connector is plugged in. The ECM if after the TCM in the network.

 

[NickTransmissions]

Thanks I will read through...and Edited my title..

Rgr...Have you attempted to reestablish communication and re-set the adapts to factory new using your scan tool?

 

[68jay]

I don’t have a scan tool that can reset, I have checked tge connection on the transmission 3 times to ensure.. starting to think it could be the BCM?

One thing I should also note is something is draining the battery, I have recharged and load tested and the battery is good, I also left it all night unplugged from the truck and had kept a charge.

 

[NickTransmissions]

I don’t have a scan tool that can reset, I have checked tge connection on the transmission 3 times to ensure.. starting to think it could be the BCM?

You have to do a fast adapt relearn anytime you do anything to the transmission beyond just a fluid and filter change. This includes the torque converter since the computer will adapt to TC degradation that shows up as drivability symptoms and/or anomalous data readings to the PCM. So you will need to acquire a scan tool that's capable of doing so...Besides, this is an excellent opportunity for you to augment your kit with a scanner since every DYI'er shouldn't be without one, especially those that own computer-controlled vehicles (early 1980s+).

I'd go over everything in the transmission area again, just to be sure no ground wires/straps are missing/loose, no wires are cut/frayed, everything is connected/plugged in, etc.

 

[68jay]

If there is already a communication “error” in my scanner, will the adapt scanner work?

 

[Fless]

Is your scanner able to communicate with ANY modules?

 

[68jay]

None.. just comes up as “ communication Error”

 

[Fless]

I'm not sure if it affects your year, but a fuse for one of the auxiliary power ports also powers the OBD port in some of these SUVs. You may want to check an OBD pinout diagram to see if voltage is at the proper pin(s). And check the power port fuses.

@Doubeleive might have a comment...

 

[PG01]

Make sure all your grounds are clean and tight. check wiring harness that you didn’t pinch anything anywhere..

 

[NickTransmissions]

If there is already a communication “error” in my scanner, will the adapt scanner work?

No, you'll need to fix the comm problem first but not having a capable scan tool handicaps you bigly. I strongly recommend you invest in one so you dont have to rely on other people (shops, etc) to do basic diag and reset functions. Autel, Snap on, Bosch, etc all make them. AC Delco's Technical Delivery System also offers subscriptions to diagnostic suites, paid on a per-vehicle basis.

 

[Doubeleive]

None.. just comes up as “ communication Error”

Did you check the fuses in the drivers side & passenger dash end cap? the obd port communication is normally shared with the drivers side cigarette power port, so on the left side check #4,8, 27, 36, 50, 52
on the right side check # 4, 50, 52
it should show in the owners manual which fuses they are if you want to double check.
there are also a couple pins on the obd port you can check with a ohm meter, if one or both of those shows a open circuit or the incorrect ohm's then you have short to ground or broken wire in the lan bus. (or as noted above a bad fuse)
i don't recall the exact pins but you can just look up gm obd lan bus pins/ohms and there should be many links to the info.

 

[68jay]

Just an update, after checking the connections for the 20th time found the issue with the transmission plug notating correctly, I now have communication but still no start.. no codes pop up..hopefully a TCM relearn will change that!?

 

[mountie]

I don't know if this helps.... A friend had a Chevy s10... The removal / replace of the torque converter required the transmission shop to do a 'GM required" learn procedure. Maybe a transmission shop may have some thoughts on this?

 

[Doubeleive]

Just an update, after checking the connections for the 20th time found the issue with the transmission plug notating correctly, I now have communication but still no start.. no codes pop up..hopefully a TCM relearn will change that!?

I don't know if there are seperate learns but the transmission relearn has to be performed while the engine is running and the transmisson temperature is at 160deg or more
so I would check the shifter position, that would be a reason for no start if it is reading anything other than park or nuetral it will not start.

 

[NickTransmissions]

Just an update, after checking the connections for the 20th time found the issue with the transmission plug notating correctly, I now have communication but still no start.. no codes pop up..hopefully a TCM relearn will change that!?

Vehicle has to be running, transmission to operating temperature prior to beginning the fast adapt relearn procedure for the transmission.

Do you have a 'No crank - no start' or is it cranking over but simply not firing up?

 

[Joseph Garcia]

Vehicle has to be running, transmission to operating temperature prior to beginning the fast adapt relearn procedure for the transmission.

Do you have a 'No crank - no start' or is it cranking over but simply not firing up?

Just for my understanding, how do you get the transmission to operating temperature? Do you drive it to warm up the transmission, even though the fast relearn procedure has not yet been started?