Several changes have been made to the 9-speed transmission (RPO M3W, M3F, M3H, M3G, M3T, M3V, M3U) automatic transmission fluid Oil Level Control system (OLC) for 2023-2024 Enclave, Encore GX, Envision, XT4, XT5, XT6, Blazer, Trailblazer, Traverse, Acadia and Terrain models. The OLC system stores fluid in the side cover as the transmission warms up.
The OLC system through the 2023 model year consists of a standpipe with a thermal door, on/off solenoid and valve. For the 2024 model year and some 2023 models equipped with RPO BCE, the following changes have been made to the OLC system.
TIP: With OLC (w/OLC) indicates the original design of the OLC system. Without OLC (w/o OLC) indicates the new design of the OLC system.
Standpipe Thermal Door
The previous automatic transmission fluid level control valve on the standpipe had a small thermal door. (Fig. 1, #1) The new style has a larger thermal door on the standpipe (Fig. 1, #2), which is necessary for the removal of the OLC components.
The larger thermal door can be used for any model year while the previous smaller thermal door can be used only on 2022 and earlier models.
Fig. 1
Transmission Fluid Valve
The automatic transmission fluid valve has been eliminated on the valve body. (Fig. 2, #2)
Fig. 2
Spacer Plate
The valve body-to-transmission case spacer plate is now covering over the port. (Fig. 3, #2)
Fig. 3
Transmission Fluid Control Solenoid
The solenoid body no longer has the transmission fluid control solenoid and related wiring. (Fig. 4, #2)
Fig. 4
Valve Body Cover
The old and new valve body covers are interchangeable. The new-style valve body cover has a plug that is used during assembly. (Fig. 5, #2) It should not be removed. The old-style valve body does not have the plug.
Fig. 5
Using the Correct Parts
During repairs of the 9-speed transmissions, the current valve body (w/OLC) components can be used in 2023 and earlier model years. The new valve body components should be used starting with 2024 models (w/o OLC). Be sure to use the correct parts for the model year being repaired.
In order to facilitate the manufacturing process, some 2024 vehicles may have been built with some old-style components. This is not a concern since the 2024 and 2023 RPO BCE transmission calibration ignores those component inputs.
For additional information, refer to Bulletin #23-NA-135.
– Thanks to Mark Kevnick
