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)
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)
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.
Fig. 9
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)
Fig. 10
For more information and part numbers, refer to #PIP6084.
– Thanks to Steve Schipansky
