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I have a 2020 non-z51, transmission failed in September 2023 at 12,000 miles. Was replaced with the redesigned model under warranty. 2,500 miles later, the car lost power and the dash said transmission failure. The problem this time was the TCU and ECU, both had to be replaced. This time not under warranty due to whomever owned it before me had installed an aftermarket TCU. Car previously pulled a 0-60 of 2.8 now, best has been 3.4. I didn't have a clue that anyone was modifying the TCU but it makes sense.
There has not been any talk of modded TCUs on the C8
Originally Posted by whtever
I have a 2020 non-z51, transmission failed in September 2023 at 12,000 miles. Was replaced with the redesigned model under warranty. 2,500 miles later, the car lost power and the dash said transmission failure. The problem this time was the TCU and ECU, both had to be replaced. This time not under warranty due to whomever owned it before me had installed an aftermarket TCU. Car previously pulled a 0-60 of 2.8 now, best has been 3.4. I didn't have a clue that anyone was modifying the TCU but it makes sense.
In the Service Manual, there is an Engine Control Module (ECM), a Transmission Control Module (TCM). I have never seen any offering for an aftermarket version of either of these for the C8. There are discussions that certain vendors (HPTuners) can modify the programming in the factory ECM. There was also at least one discussion about a TCM mod, but I think that may have been a mistake.
The point is, seems odd that warranty claim would be denied due to an "aftermarket" TCM - there may be no such thing. I suppose it could be denied if an owner replaced the TCM with another GM sourced C8 TCM, but not properly calibrated or programmed. Some programming procedures are requires when a TCM is replaced - perhaps they were not followed. And there were some factory provided TCM calibration updates. But those can typically be performed without replacing the module (unless the module is defective - which should be a warranty issue).
In the Service Manual, there is an Engine Control Module (ECM), a Transmission Control Module (TCM). I have never seen any offering for an aftermarket version of either of these for the C8. There are discussions that certain vendors (HPTuners) can modify the programming in the factory ECM. There was also at least one discussion about a TCM mod, but I think that may have been a mistake.
The point is, seems odd that warranty claim would be denied due to an "aftermarket" TCM - there may be no such thing. I suppose it could be denied if an owner replaced the TCM with another GM TCM, but not properly calibrated or programmed. Some programming procedures are requires when a TCM is replaced - perhaps they were not followed. And there were some factory provided TCM calibration updates. But those can typically be performed without replacing the module (unless the module is defective - which should be a warranty issue).
If the title of the post above is a reference to my statement about "another GM TCM".....no, I was not referring to another different GM model. I meant that the previous owner could have installed a factory C8 replacement TCM. They still require proper programming and set up. I will fix my post to clarify that.
And yes, that was my point too - something is odd.
My 20 trans just failed. Did your issue get resolved?? How long did it take??
Originally Posted by Petro1958
Just picked up my new 2024 C8 after a
16 month wait. Drive it home and wasn't happy with shifting and making a
noise in reverse. Turned around and
brought it back to dealership. Needs a
new transmission......say what?
3-4 week wait they say. I was also told
it would be the newer updated version.
1st loan payment due before ever driving the vehicle.
According to my build I have a new transmission case in my C8. Last week did get a new pan installed because the current one was defective. Replaced pan/gaskets/studs and obviously fluid.
