I think back to the lead-up to the year 2020 and the C8 Corvette, and we distinctly remember how excited everyone was about the Corvette finally receiving an 8-speed automatic dual clutch transmission from TREMEC. Unfortunately, this transmission has caused more than a few headaches for both Chevrolet and its customers, and it’s not uncommon to know someone whose C8 has had a replacement transmission (or two).
Looking back now six years, the transmission issues are less of an issue these days than what they were previously as TREMEC and GM have made additional design and interior changes to the DCT to fix some of those earlier issues. But they still do happen and now GM is making parts available to dealers so that they can be repaired as opposed to replaced.
That’s great news for owners, because at some point our warranties do run out, and no one wants to be on the hook for a $20K+ replacement transmission if it can be fixed instead for a fraction of that cost. At least that is the hope!
Chevrolet has details about one of these transmission fixes in a recent GM Techlink article and while it’s not something the average shade-tree mechanic should think about tackling themselves, it does provide a look at what this particular fix is done and the relearning that has to happen with the software.
For this GM TechLink article, the solution fixes a faulty Park Lock Valve that previously required the entire transmission assembly to be replaced.
Transmission Park Lock Valve Parts Released
Park lock valve-related faults on 2020-2025 Corvette models were previously repaired by replacing the transmission assembly (RPO M1L, M1M, MLH). Parts and service procedures are now available for servicing the park lock valve and harness, eliminating the need for transmission assembly replacement. (Fig. 7)
There are several Service Information documents that deal with park lock valve conditions, including Bulletin #23-NA-176, which covers park sensor drift, and Bulletin #23-NA-197, covering a dislodged snap ring in the direct clutch assembly. (Fig. 8)
If it’s determined that the park pawl actuator needs to be replaced, here are some helpful tips.
Refer to Service Information Doc ID 6837160 for park pawl actuator replacement instructions.
After repairs, the Transmission Control Module (TCM) will need to be programmed with a VCI number from TCSC. The new park pawl actuator will need to be fine-tuned to the particular transmission being repaired, and the calibration allows for the learn to be performed.
The park pawl actuator PUN will need to be characterized, so it will be helpful to take a picture of the PUN before transmission reinstallation. The PUN is 22 digits and etched/printed number is very small. (Fig. 9) It begins with PO. If the PUN is not characterized, the vehicle may not start. The vehicle must be able to be started to perform the relearn. If the correct PUN is not used, it may be necessary to remove the transmission again to confirm the PUN.
The park lock valve learn must be run after TCM reprogramming and characterization, improper calibrations in the TCM will result in a failure 2F01 when attempting to run the learn.
The wiring harness will need to be replaced if any retainers are broken when removing the harness.
Check out the December 2024 Emerging Issues seminar for a video providing detailed instructions on feeding the park rod back into the transmission using the Plunger Shaft Lifting Tool (Fig. 10, #1) and Park Pawl Engagement Tool. (Fig. 10, #2)
For more information and part numbers, refer to #PIP6084.
Source:
GM Techlink via MidEngineCorvetteForum.com
Related:
GM Issues New Service Bulletin for the 2025 Corvette’s Braking System
GM Issues Technical Service Bulletin for 2025 Corvettes Over Contaminated Front Lift System
GM Really Wants You to Follow the Maintenance Schedule for Your C8 Corvette’s Transmission
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They need to be focusing on taking care of the recall on the Z’s rather than focusing on less important fixes that aren’t a HAZARDOUS FIRE RISK to their customers (over 25k at risk) that own and are in possession of these vehicles needing the fuel diverter installed so we can enjoy our vehicles! More importantly GM needs to be more transparent with not only their customers but with the dealerships which at this present time know NOTHING in regards to the fix nor when customers will be able to bring their vehicles in for this FIX!
I’ll never purchase another GM vehicle again with this type of lack of customer service for their loyal customers!
UNACCEPTABLE!
I 1000% AGREE WITH gary sorci
Absolutely it is i purchased a z06 3lz convertible August 21 the day the stop sale went into affect and i am still waiting for my car why is that also i was in bowling green two weekends ago and they are manufacturing new z06’s with the part on them why in the world is this happening when you have people that have purchased one and can’t get them fixed
Mary is still getting her year end bonus
Instead of a new $20,000+ you will have the privilege of paying $14,000+ for the repair and enduring the inconvenience – if you expect to continue driving it. I wonder if the repair insurance outfit that’s on TV constantly will totally cover C8s?
gm transmission issues ? What else is new? Get an extended warranty for 5K ? No C8 for me!
Will this be a gm recall
GM/Corvette is just focusing on big production numbers on the C8, Corvettes, not quality workmanship. Secondly, the Chevrolet Dealership’s in my region,(northeast) fail to have a sufficient amount of “trained” mechanics to work on the C8, Corvettes not.
Say it after me. It is cheaper to design major components of “American” cars in the US, make the parts in China and assemble in Mexico. 2019 Equinox, 63,000 miles. Symptom, transmission slips when cold. Traded in on a Bronco Sport. Vehicle 2, 2015 Chevy Silverado. Transmission issues arise at 149,000 miles right after it’s 3rd recommended service. Traded in on a 2024 Ford F150. Now your having issues with a transmission on your most expensive car? I guess pleasing the investors are making you buckets of money huh. Better change that motto before your stock dumps and you end up like Chrysler.
Oh look at all the crybabies.
LOL.
As if GM is the only manufacturer with recalls.
Go throw another coat of Zaino on fir your next cars & coffee.
Provided there’s no chance of rain.
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